My list would go as follow:
5. Turok: This game got blasted by a lot of people because it didn't have the guns from the old Turok games. Still, the stealth gameplay (if you want) and the environments in the game are really interesting. This recreation of the Turok universe makes a lot of sense and I would like to see more of it;
4. Gears of War: Seriously, I didn't know how to approach this game when I didn't have a HD console before (I thought it was a "real man's game," if you know what I'm saying...), but it turned out to be awesome for real! I'm glad I decided to play this on co-op first too, it was really worth it;
3. Dead Space: I was amazed by the story and the atmosphere in the game. Not really scary, just really disturbing. The gameplay and UI were really interesting. I can't wait to see the sequel to this new series;
2. Bionic Commando: Even though the game flopped really hard, the guys at GRIN (R.I.P....) did a good job at recreating the swinging mechanics from the old 2D games, and I couldn't have been happier to see RAD Spencer again! Some of the things they did in the game amazed me, and the final hours of the game are quite something. Capture the flag on multiplayer is great too. Too bad we will probably never see a sequel to this sequel;
1. Persona 4: I gotta admit, I am spoiled by Square's amazing presentations in their games, but this little game from Atlus still contains a lot of heart into it. Great little piece of software that came out of nowhere in this generation of high-def consoles!
I guess Resistance 2 can get a special mention as well. I enjoyed it more than Killzone 2!