Tbh The only strong point that AMD's cards have against Nvidia's is the prices. They have very decent cards for the mid-range price level. I remember back in 2011 when I bought my HD7750, I didn't go with an Nvidia because I couldn't afford them. The only one I could afford was the 8800GT but it was already old by that time so I had to pick AMD, and I'm glad they were there to cover me.
As competing brands, I prefer Nvidia simply because they're always ahead of AMD when it comes to performance cards, but then again I really want to support AMD even without using their cards simply because the competition is a good thing for us consumers. My current PC has an Nvidia GTX 970, but my old PC (which I gave to my young siblings) is still in very good condition with that 7750. It's a really powerful card considering its price and size, not to mention low power consumption (that PC runs on a 400W supply). Things are looking quite grim for AMD though. Apparently Google may start manufacturing CPUs as well, guess they'll replace AMD in that market?