This is how I rank the games you listed
1. COD4 (The best COD IMHO)
2. Halo 3 (COD4 barely edges it in my book)
3. MW2 (Fucking ridiculous, but it is fun)
4. Black OPs (A little burned out on these by now, but nothing really wrong with the game)
5. Halo Reach (THIS FUCKING FRIED RICE STINKS!)
lol at KZ2