Is the Mini more powerful than the 21.5" i5 iMac?

There are important differences between the Mac mini you want and the iMac. First of all, both Macs have got a Quad-Core processor, but the Mac mini has got a Intel Core i7 instead of the Intel Core i5 of the iMac. In this case, the Mac mini has got a better performance.

However, I don't think that you can avoid talking about other important features. The iMac comes with 8 GB of memory (but it's not easy to add more after buying the Mac), and it comes with a dedicated NVIDIA GeForce GT 640M that makes the difference with the integrated Intel HD Graphics 4000. If you are going to use games or even watch HD movies, buy the iMac because the Mac mini won't be able to run them.

If the computer is for a basic use, then buy the Mac mini. It will be cheaper and the upgrade possibilities are bigger

You can watch HD movies with that graphic, but it may be slower than with the graphic of the iMac. In my opinion, games are decisive to choose between the iMac and the Mac mini. Also, as you want to use AirPlay Mirroring, I think that the iMac is the best option. Anyway, it's up to you

Mac mini all the way. HD movies run fine on the Mini, as does light games (Civ V, Civ IV, Portal) but I do most of my gaming on the Xbox 360.

AirPlay, again, runs absolutely fine on the Mini. I would say that the base iMac is really only a good option if you need a new display or for some reason you need it to be AIO. Although, mende1 is correct in stating that the iMac does have 8GB of RAM, but the Mini is more expandable.

You will be sacrificing overall performance in terms of the CPU with the iMac.

I just checked on the US Apple Store (I'm in the UK) and the cost of a Mini with a 2.6 i7, 1TB Fusion Drive and bluetooth keyboard & trackpad (or mouse) is £1075/$1287. This would be a very fast machine.

The only issue with the integrated graphics is if are

going to do things like advanced video editing, complex

3D development work, or heavy duty gaming. For use as

a general purpose computer or home theater computer

it will perform quite well. It will also work quite well for

any type of application that does any heavy duty number

crunching.

So, if gaming is a concern, just Google HD4000 and gaming

and what sort of performance is seen and what sort of level

of gaming you could expect to see.

As a music/video entertainment center, go with the Mini for

sure. Personally, I am using an old 2010 Mini for that purpose

and it handles any 1080p HD content I throw at it. So the new

ones should be more than adequate.

I used to have a 2009 24" iMac and now have a 2010 Mini hooked up to my 42" TV. For general use the performance is very compatible, but you cannot get a 42" iMac. Of course, both computers support duel monitors. I had my iMac connected to a 37" TV, but the graphics were maxed out and it used to shudder a little watching movies on one display and surfing the net on the other. However, I have the mini connected to a larger TV and a 24" monitor, but don't get the graphics issues. I'd go with the Mini.

There is much more to graphics performance than just having

more graphics memory. The discrete GPUs are designed

specifically for graphics performance. Also, the memory

is dedicated to the GPU. Integrated GPUs, such as the HD4000,

share system RAM and such have their ultimate capabilities

limited by system RAM bandwidth. Also, there are design

limitations of integrated graphics because they are, well, integrated

on the same chip as the CPU.

So, as far as graphics, discrete GPUs will almost always outperform

integrated GPUs.