CoD4. I'm a console-tard and I suck at FPS. =P
Umm...Can't really think of anything else at the moment, because, usually, when I love a game, I play it so much that I inevitably become great at it.
...Oh! Yeah, I played StarCraft again recently, and, after years of being spoiled by RTSs where you can zoom in and out and win just by having the most upgrades, yeah, I was nowhere near as competent with it as I had been years ago. Plus, the computer is a cheating dick.