Which mac is best for gaming and university work such as photoshop

For gaming and programs such as Photoshop you want as much power as possible. Are you looking for a Desktop or Laptop? Will portability be something you are looking for with photo's etc?

The iMac is a fantastic Desktop, I use mine for MMORPG gaming and the 27" screen is superb. An iMac will have no trouble running photo/video editing programs either, and it's probably one of Apple's best looking products. I have a 1TB iMac which I formatted and installed Windows 7 on 25% of, results were amazing and my games worked just fine.

As for Laptops you will probably want a MacBook Pro Retina, perfect for Photoshop. If you've not yet used a Retina Display on a Mac you're missing out as they are truly beautiful. A MBP also packs enough punch for all your gaming needs, you also get the portability with a Laptop.

Here you can compare the prices and specs across the MacBook Pro's and the iMac's:

MBP: http://store.apple.com/uk/buy-mac/macbook-pro

iMac: http://store.apple.com/uk/buy-mac/imac

Ultimately the choice is yours, if you're still stuck head into an Apple store and ask the same question, I'm sure they will be more than happy to help you out.

A Mac Pro configured to the maximum limits will be the best for games:

http://store.apple.com/us/buy-mac/mac-pro?product=MD878LL/A&step=config

Ciao.

Of course the higher the spec machine the better the game will run, and a Mac Pro is the daddy of computers. However beyond a certain spec you will see no real difference in the games and it's ability to perform well.