As a gamer/hobbyist miner, IMO there is no reason to buy nvidia at this point. Why buy a nvidia card when I can run my radeons when I'm not gaming and essentially have my cards pay for themselves after only 1 or 2 months? I enjoyed nvidia products for very many years but I am not going to turn down what is essentially a top tier, free, crossfire setup. The litecoin difficulty rose as more and more AMD cards were added to the network but seems to have stabilized as the supply of cards dried up. Litecoin mining is still profitable assuming you pay a reasonably low rate for electricity. Besides, the money nowadays is not really in bitcoin or even litecoin anymore, but other scrypt based alt coins such as dogecoin/gridcoin where the profits are potentially enormous for the early miners.
I have been an avid nvidia follower for most of my gaming career but things have shifted with the litecoin craze. An HD 7950 that sold for <$200 last year now sells for 1.5x that, used. So a gamer who bought a 7950 or 7970 in the past year actually saw the value of their card RISE over time, something that I never could have imagined. In terms of performance, all of my AMD cards overclock extremely well, far better than anything I've been able to do with my nvidia cards. They also perform well for all the games I've tried and the drivers are not nearly as bad as people make them out to be.