Of all the fighting games I've tried, I find none to be any better than
Garou: Mark of the Wolves on Neo-Geo. There's a PS2 port available only in Japan. The game just never stops being entertaining and challenging no matter how many hours one puts into it. Characters are funny and varied. Animation is of good quality and pushes the jurassic Neo-Geo hardware to its limits. My favorite character is Hotaru, and her fighting style is oddly similar to the one played by Ling Xiaoyou in the Tekken series.
When it comes to 3D, the one I like the best is Virtua Fighter 2. Even if technically, Virtua Fighter 4 is more accomplished, I guess that the old-school charm of this Model 2 fighter makes it more attractive. Probably the game in which I've invested the highest amount of time ever.