You guys are going to laugh but I think the game I've beaten the most is Bionic Comando on the nes lol I don't remember how many times I've beat it but I know I've played it a lot and beat it a good 10 times lol.
There's also FF8 that I've beat a good 4-5 times, SMB3 between 5-10 time and Super Mario World another 5-10 times.
My favorite games for this gen:
1. Gears of War 2. MGS4 3. Killzone 2 4. Halo 3(Underated by many) 5. Mass Effect