1.  Persona 4

2.  Street Fighter (pretty much all of them)

3.  Mortal Kombat  (all except the PS2 ones and NOT MK vs DC)

4.  Portal (both)

5.  Guilty Gear (all except Overture)

Bonus round:  Marvel vs Capcom 2, Ratchet and Clank (series), Kingdom Hearts (1 and 2 and Birth by Sleep), God of War (only played 3 but loved it), Final Fantasy (7 and 10, I need to play the originals), Super Mario Brothers (pretty much all of them), Sonic the Hedgehog (all before next-gen), Super Smash Brothers (series), Mario Kart (all).  Legend of Zelda: Ocarina of Time (I love the other ones but this is my favorite).  Batman: Arkham Asylum and City.  The lego games.  Puzzle games like Tetris and such.  Resident Evil (except Outbreak and the games past 4, they aren’t bad, just… started to lose the Resident Evil feel).  Silent Hill 1, 2, and 3.    

Random throwbacks:  Mystical Ninja starring Goemon.  Super Mario RPG.  Banjo Kazooie (the N64 one NOT the 360 one).  Bust a Groove 1 and 2.   

Wow I knew this was going to be long  ^^;;;