You should go for GTX 660 at that price point
I am fine with nvidia cards. In fact they are the only kind I have ever had (haven't tried Radeon yet). But I figured since my new motherboard/processes are AMD I would go for the trifecta. I don't know if it matters or not.
Is a GTX 660 that much better than the 7850?
If the GTX is the better choice I have an EVGA card in mind already.