Some of my most valued cards were my first GPU, a RIVA 128 (Viper 330). That was the card that made me ditch consoles for good. Another was my 9700pro that replaced a Geforce 2 GTS as the fps boost was incredible. However I still hold my 4670 up as the best bang for the buck ever. Bought it for around $35 new over two years ago and it allowed more than ample performance for 1280 gaming,
My current unlocked 6950 is a contender given its value in the face of current GPU pricing. We'll see how the performance holds up over the next year before I pass final judgement.
Ah I knew I forgot one or two. The Riva 128 & Riva 128ZX were good cards speed wise, but the image quality sucked ass. Anyone remember the Riva TNT? TNT2/Ultra?