iMac, Macbook Air or rMBP?

So guys, here´s the deal: I have a mid 2009 white macbook, I loved it trough the years but it´s time to make some changes.

I live in Brazil and apple products are incredibly expensive around here - that´s why I still have good and old whity.

My problem is: in november I´ll have enough money to buy a new mac (I told you this things are very expensive here!) So, should I buy an 21,5´ iMac, 13´ Macbook air or 13´ Retina Macbook Pro? Keeping in mind that they are aproximetly the same price here. (Crazy, right!?) and I would like a computer where i can edit gopro videos, photos, and occasionally play Diablo III and Starcraft. In terms of performance, of course the iMac is the way to go, but I´m just crazy about the protabillity of the MBA! The question is: what is more frustrating: the lack of portability of the iMac, or the lack of performance on the MBA??

My third option is to wait until July 2014 to upgrade, when I´ll go to NY and I would by an 15´ Retina MBP - paying almost 1/3 of the price here.

Sorry for the long post, but I´m really in doubt here!