I don't have brand loyalty but I can easily say Nvidia won these past few years. My last card before the GTX 1070 was AMD 7870. before that, 6870, before that, 5850. before that, 3650. all AMDs/ATis. not because of loyalty but because I found them the best choice when I was picking what to get. Now Nvidia is currently the best choice, imo even with Vega coming out. for gaming ofcourse.
I'm hoping though that AMD up it's game so that the consumers benefit. better performance and prices for everyone! for me AMD underperforming is one of the factors as to why Nvidia and Intel are having a lot of refreshes. Nvidia is kinda fine because they still did a big jump with maxwell and pascal, even without competition from AMD, maybe their scientists are just too good, maybe despite the huge performance increases they are still holding back, waiting for AMD(hence the sudden 1080Ti release that killed one of their own... the first pascal Titan X, to scare off AMD)
I kinda hate intel though because they really took advantage of the bulldozer failure... little improvements over their i7s and requires expensive mobos to just change the multiplier. man I reached 4.5GHz on my 2600k with just a p67 chipset, can't do that now, you need a Z board.