there's not much to choose from. screwd amd. they deliver what they promised, but it never lives up to it's hype. for an example, amd promised a software likes nvidia's shadowplay. they did that. however, whilst shadowplay uses the card differently, and makes it to a video recording without any fps drops at all, amd's software was able to drop 30 frames constantly on an older card.
anyways, just choose anything from nvidia. you can trust them. you can't trust amd. (comes from previous amd owner. they released drivers. had to revert shit because the drivers were broken and they never released any fix to that.)
so what do you choose from nvidia then? depends on what you are out for and what money you're able to spend on it. as i've already said in alot of previous posts, the 750ti-780ti is decently affordable and has really good performance. you definently get what you pay for, if not more. if you're out for hardcore gaming/a card which can run new games perfectly, i'd definently say the 970-980/970ti-980ti is what to go for. they're a bit pricey, though, but again, you get what you pay for, if not more.
then there's the 600 series, which yes, is pretty good, but you can get more performance for the money (looking at the long run. probably cheaper when you first buy it, but you could've waited a month and gotten yourself that little bit of extra money to get those much better performance cards).
just remember, if it has ti after it's name, it's stronk af.