PS2? I only keep it as a museum item now, seriously it looks like new, I even got a perfect box. It was a slim P12 or so I couldn't remember.
Back then I play Ace Combat, Metal Gear Solid, Onimusha, God of War, Price of Persia, a few other random games that I couldn't remember. I like MGS3 the most as it feels like a movie. I love watching cut scenes.
I play all Valve games, Left 4 Dead series, Team Fortress 2 is the two I played a lot (well TF2 - love it). I also play RTS game (Company of Heroes) multiplayer.
I found no interest title (for me) on DS, hence I didn't get it. The sole reason for me to buy PSP is the amount of Juice (eroge/visual novels). I have 5 x 32GB memory sticks (160GB total) loaded with many eroge/visual novels :p
Finally, I don't play game on consoles if it's available to PC, especially the FPS genre (must be PC for me), and except adventure game that is made natively for consoles (Assassin's Creeds), (I banned all Ubisoft title on my PC and its new DRM anyway)