If you are on the market for a desktop Mac you may be wondering whether to spend your money on an iMac or a Mac mini. There's also the Mac Pro to consider, but that's a very high-end Mac, with a very high price. 
Depending on your needs there is likely to be a desktop Mac to suit. We'll investigate this below.

iMac verses Mac mini: specs compared

There are six different iMacs and three different Mac minis with a number of build to order options available. Below we will weigh up the differences between each of the different models. A new iMac may be set to launch this summer. 

iMac specs

The iMac is an all-in-one desktop computer with an integrated display. There are a mixture of sizes available: a 21.5-inch and a 27-inch (that's a 21.5- or a 27-inch screen measured diagonally) and you’ll find a variety of processor speeds (all processors are Intel’s Haswell generation), hard drive sizes, graphics cards and RAM options.
There was a new low-cost iMac model introduced in the summer of 2014, this was the 21.5in iMac, that offers a 1.4GHz dual-core processor with 8GB memory (not upgradable even at point of purchase as it is soldered on), Intel HD Graphics 5000, a 500GB hard drive, and costs £899.
Joining the iMac line up at the end of 2014 was the Retina 5K iMac. At the other end of the scale from the £899 iMac, this 27in model offers a 3.5GHz Quad-Core i5 processor with 8GB RAM as standard (you can add 16GB or 32GB RAM and a 4.0GHz Quad-core Intel Core i7 at point of purchase for a price). That iMac will cost you £1,999, more than double the price of the entry-level model, even more if you spec it up to the max.
There are also four other standard versions of the iMac to choose between. These were introduced in October 2013 and have not been updated by Apple since. 
The standard processor in those models is an Intel quad-core i5 that ranges from 2.7GHz to 3.4GHz (although there is a configuration option of a 3.5GHz Quad-core Intel Core i7). Each iMac comes with 8GB RAM as standard (configurable to 18GB or 32GB at the high end) and a 1TB hard drive as standard (configurable to 3TB or a range of SSD options or a Fusion Drive, which combines an SSD and a hard drive).
One of these standard models offers the Intel Iris Pro Graphics card – a step up from the Intel HD Graphics 5000 in the £899 model. The rest offer variants of the NVIDIA GeForce GT series (750M, 755M and 775M). This dedicated graphics card has its own 1GB memory on most models (2GB on the high-end model, configurable to 4GB).
In terms of ports all the iMac features an SDXC card slot, four USB 3 ports, two Thunderbolt ports (Thunderbolt 2 on the Retina model), Gigabit Ethernet and a Mini DisplayPort output. Each iMac comes complete with an Apple Wireless Keyboard and Magic Mouse.
Product
GHz
RAM
Graphics
Storage
Price
iMac
1.4GHz dual-core
8GB
Intel HD Graphics 5000
500GB hard drive
£899
iMac
2.7GHz quad-core
8GB
Intel Iris Pro Graphics
1TB hard drive
£1,049
iMac
2.9GHz quad-core
8GB
NVIDIA GeForce GT 750M with 1GB
1TB hard drive
£1,119
iMac
3.2GHz quad-core
8GB
NVIDIA GeForce GT 755M with 1GB
1TB hard drive
£1,449
iMac
3.4GHz quad-core
8GB
NVIDIA GeForce GTX 775M with 2GB
1TB hard drive
£1,599
iMac
3.5GHz quad-core
8GB
AMD Radeon R9 M290X with 2GB
1TB Fusion Drive
£1,999
Watch our video to find out more about the 203 range of iMacs that are still on sale.

Mac mini specs

The 2014 Mac mini fits inside a tiny 20cm square box that's less than 4cm deep. There is no monitor, mice or keyboard included with the Mac mini.
Apple updated the Mac mini range at the end of 2014. This box is sold in three configurations.
The entry level Mac mini and the entry-level iMac introduced in mid 2014 share a lot in common. The cheapest Mac mini has the same 1.4GHz dual-core Intel Core i5 processor and integrated graphics chip (the Intel HD Graphics 5000) as the entry-level iMac. It also features a 500GB hard drive. It is essentially the same specs as the £899 iMac, but costs just £399, that's a saving of £500, more than enough to buy a separate monitor and keyboard and mouse.
The other Mac mini models offer quite a boost from the entry-level model, although they lag behind the now discontinued 2012 Mac mini. Read more about the comparison between the 2012 Mac mini and the 2014 Mac mini here.
The 2.6GHz dual-core i5 Mac mini, offers 8GB RAM, a 1TB hard disk, and Intel Iris Graphics. It costs £569. It is possible to upgrade the RAM to 16GB at point of purchase. There are also options for configuring the Mac mini with flash storage or a faster i7 processor.
The 2.8GHz dual-core i5 Mac mini, offers 8GB RAM, a 1TB Fusion Drive (combining a hard drive and flash storage), and Intel Iris Graphics. It costs £799.
These two Mac minis are comparable to the processors inside the 13-inch Retina MacBook Pro, but you can expect the faster flash storage in the MacBook's to give those models a boost. 
Product
GHz
RAM
Graphics
Storage
Price
Mac mini
1.4GHz dual-core
8GB
Intel HD Graphics 5000
500GB hard drive
£399
Mac mini
2.6GHz dual-core
8GB
Intel Iris Graphics
1TB hard drive
£569
Mac mini
2.8GHz dual-core
8GB
Intel Iris Graphics
1TB Fusion Drive
£799

iMac versus Mac mini specs: Buying advice

In terms of specs the iMac is a better deal than the Mac mini because it features more modern processors, more RAM, and better graphics. It also features an integrated monitor. However, if you wanted a FireWire port or an HDMI port the Mac mini offers one. It is unlikely that the new Mac mini will offer a FireWire port, so you may wish to buy one before an update happens. 

iMac verses Mac mini: Storage

The storage options are very similar across the iMac and Mac mini ranges. Each offers a 500GB hard drive at the entry-level, a 1TB hard drive at the mid-range, and a 1TB Fusion Drive at the high end.
We’d say that the fact that you can pick up a Fusion Drive as standard on the £799 Mac mini is a point in its favour, or add £160 to the price of the mid-range Mac mini, or £200 to the £399 model, to upgrade to a Fusion Drive. We recommend doing so because having a Fusion Drive will make a huge difference to the speed at which your Mac operates.
The iMac range also offers various Fusion Drive options across the range.  You can add a Fusion Drive to the entry level iMac for £200 – we recommend you do that because with the Fusion Drive this machine is as good as the next step up and will still cost less – read or review of the £899 iMac with Fusion Drive here. The Fusion Drive upgrade is £160 across the other iMacs.

Buying advice

The storage upgrade options are the same, but the starting price is so different that you can essentially get a pretty decent Mac mini for less than the cost of the entry-level iMac. 

iMac verses Mac mini: Ports

When it comes to ports, the Mac mini has one thing in its favour, it includes an HDMI port, which makes it really easy to plug it into your TV, making it the perfect choice if you wanted a media centre for your living room. You could use an adaptor to turn the Mini DisplayPort output on the iMac into HDMI, but at an extra cost.
Prior to Apple’s 2014 upgrade to the Mac mini we’d have been able to say that the other port that the Mac mini includes that the iMac doesn't is a FireWire 800 port. Unfortunately that is no longer the case. The old MacBook Pro is the only Mac that still feature this port.
Other ports on the Mac mini include Gigabit Ethernet, two Thunderbolt 2 ports, four USB 3 ports, the HDMI port, audio in and a headphone port, an IR receiver, and an SDXC card slot.
The ports on the iMac are as follows: Gigabit Ethernet, two Thunderbolt ports (only the Retina iMac has Thunderbolt 2), four USB 3 ports, a headphone port, a Kensington lock slot, and an SDXC card slot.

Buying advice

Here again the Mac mini kind of has the edge because it has the HDMI port, which is great if you were hoping to attach it to your TV. Of course, the iMac doesn’t need to be connected to your TV because the screen is included. Which brings us on to our next point…

iMac verses Mac mini: Display options

The iMac comes with an integrated display, with 21.5in or 27in options. The ultimate iMac comes with a Retina display boasting an astonishing 5120 x 2880 pixels, that’s a total of 14.7 million pixels at 217 pixels per inch. 
The other iMac displays may not be as ground-breaking, but they are still of good quality. They feature IPS technology (in-plane switching), which makes a huge difference to the colour vibrancy and reproduction. Earlier models of the iMac were criticised because their display was considered too reflective by some, luckily the 2013 model remedied this and the Retina iMac went one step further, adding a special film that improves the off axis viewing.
However, if you are a designer and need colour accuracy, you might be better off with another display – the good news is you can plug another display into the back of your iMac and have two displays.
The Mac mini doesn’t come with a display so you will need to either use one you’ve already got, or purchase one separately. You can pick up a separate monitor for around £100. Or you could spend more than twice as much as the cost of the Mac mini and purchase an Apple Thunderbolt Display for £899.
As we mention above, you can also plug your Mac mini straight into your widescreen TV, making it ideally suited as a media centre in your living room. We wouldn't recommend working on a Mac that had a television screen as a monitor, though.

Buying advice

The key difference when choosing between the Mac mini and an iMac is the presence of the integrated display on the iMac. If you add the cost of a decent display to the price of the lower-cost Mac mini it doesn't look like such a cheap option.

iMac versus Mac mini: upgradability

One of the best features of the 2012 Mac mini was the fact that it was more upgradable than any other Mac. On that model it was possible not only to upgrade both the hard drive and the RAM, but crucially these could be updated at any time and using parts purchased separately, rather than being stuck with the upgrade options offered by Apple at point of purchase.
Sadly the new 2014 Mac mini is not so upgradeable. Apple has decided to solder the RAM in place, as you will see if you read this article: Mac mini 2014 v 2012 model, comparison. You can still upgrade the storage on the Mac mini, so that’s one factor in that Mac’s favour.
iFixIt.com gave the old Mac mini a reparability rating of 8 out of 10 in its teardown. The new 2014 Mac mini features RAM that is soldered on, so it is impossible to update it at any time after purchase. iFixIt gave the Mac mini a 6 out of 10 this time round.
Attempting to upgrade the iMac is not for the faint hearted. If you aren't prepared to pull your Mac apart, you may be wise to fully spec out the iMac at point of sale. There are a number of build to order options, so if you think you will need more RAM or a bigger hard drive, or an SSD at a later date, you are advised to do that when you buy it. However, you will pay much more for the extra RAM and storage than you would if you did it yourself.
You can't add your own RAM to the 21-inch iMac without a lot of hassle. You'll need to take the iMac apart and cut through a lot of adhesive to get to the memory slots, which are hidden behind the logic board. So, unless you really like to get your hands dirty, you are stuck with Apple's base 8GB or expensive build-to-order options. As for other upgrades, don't even go there. The CPU is soldered to the logic board so it can't be replaced if something goes wrong. 
Upgrading the RAM in a 27-inch iMac is easier though – at least for now. We explain how to add extra RAM to a 2013 iMac in this article. According to iFixit's teardown of the 27-inch iMac it is possible to replace the hard drive and CPU, but you'd need to cut the adhesive.
The Retina iMac scored 5 out of 10 for reparability on iFixIt. The 21.5in iMacs score even lower: 2 out of 5 for the entry-level 21in iMac

Buying advice

The Mac mini used to be the Mac for the kind of people who liked to tinker. Now that Mac is not as easy to upgrade down the line. You won’t be able to touch the RAM as it is soldered on, for example.
If you buy an iMac (especially the 21.5inch model) then you’re more likely to end up using that specification of machine from then on. Of course, this should be balanced against the fact that the iMac has better specs to begin with.

iMac versus Mac mini: which Mac is best value?

The Mac mini is Apple's cheapest Mac at £399, but as we noted above, that price doesn't include a monitor, or a mouse and keyboard. Add even the cheapest monitor (around £150) and the cheapest Apple keyboard and mouse options (£40 each), and you are looking at around £629. That makes it comparable to the £899 iMac, which has the same spec than the Mac mini. Of course to compare like for like you’d be looking at a more expensive monitor to go with your Mac mini – but you may already own that monitor… So in terms of the entry level iMac and Mac mini it certainly looks like the Mac mini is the best value.
The iMacs and Mac mini’s are less comparable outside of this entry level category as the Mac mini features dual core chips, while the iMac features quad core processors. So even if you take the most highly specced Mac mini – the £799, 2.8GHz dual Core model and compare it to the £1,049 2.7GHz iMac, that iMac does have a quad-core processor and Intel Iris Pro Graphics, compared to the 2.8GHz dual-core processor and Intel Iris Graphics.  The one thing in that Mac mini’s favour is the 1TB Fusion Drive which will help boost the speed of that model. The iMac will cost you £250 more than the Mac mini in this case, and another £160 if you wanted to add the Fusion Drive. That’s at least £250 for a quad-core processor, which is essentially the only difference, apart from the display, obviously.
Beyond those two iMacs there isn’t really a comparable model to the Mac mini range. 

Buying advice

We’d recommend the entry level £399 Mac mini over the iMac. But beyond that it gets a bit murky.
If you are only considering the entry-level Mac mini, the price of the iMac is significantly higher. You could equip the cheaper Mac with a monitor, mouse and keyboard, and still have cash left over. There is no doubt that the Mac mini is the cheapest way to buy a Mac.
If it's cheap you are after, it's worth considering the £749 MacBook Air which has exactly the same specs as the entry level iMac and Mac mini – that same 4GB memory, 1.4GHz dual-core Intel i5 processor. And the Intel HD Graphics 5000. The only difference is that it ships with 128GB flash storage – which will make it faster than the Mac mini (and if you need the storage you can buy a separate hard drive. If also features an 11in display which may be big enough for your needs. That entry-level MacBook Air costs £350 more than the Mac mini.