MBA or MBP with Thunderbolt Display

Hello boys and girls,

I wanted the buy a new Macbook. The problem is, that I use Photoshop, because I am a web designer. I read, that the Photoshop can run on the MBA, but it is slow.

Now I wanted to ask YOU, if I should keep my MBA 13'' (2011) and buy a thunderbolt display or if I should get a MBP with a thunderbolt display.

Thanks.