oh this is a dificult one but i I had to narrow it down, i'd say i spent alot of time with Sega GT, Grandia II, and Power Stone. Or those ones most recently.
Now that I think about it, thats not even the tip of the iceberg. I spent way too much time with the DC I have atleast 50 legit games and I've played allof them to death, and a hell of alot more non legit ones. Just off the top of my head MVC1/2, HOTD2, SA1/2, CVS, virtua tennis, soul calibur, SF3 I've put atleast a day of gametime into each.