Yeah Tekken is the best by default if you like that genre because it's a retail game as a downloadable, basically should be in the same category as Warhawk, Socom and stuff not the other classic downloads or smaller games.
Beyond that, in the classics my two favorites are easy: Symphony of the Night (one of the best games ever made) and for good fun with a buddy or even online, Mortal Kombat II with online support.
In the original games department my favorites have been as follows:
1. Super Stardust HD (easily first)
2. Calling All Cars (amazingly fun to play with other people, playing alone is not that good)
3. Lemmings (great game to kill hours with)
4. Flow (if you like very 'out there' games and is a lot better in co-op)
Thanks to Blacksaber for the sig!
