Oh wow, Riva TNT series, man that brings me back. Haha. That was the first video card I ever purchased. Followed by a Voodoo3 card just so I could play Freespace. Not long after that I found this cool sim called Flanker...
Oh such wonderful nostalgia!
Anyway, back to topic, I also recommend Nvidia. I had two AMD/ATI cards before and always had issues and sub-par performance. I also like the added benefit of things like PhysX and CUDA. I know AMD is trying to play catch-up, but Nvidia has the clear lead in offloading processes to a GPU. (Minus bitcoin mining like Skatezilla mentioned.)