I personally like COD4. Because I like realistic games. I mean you can't jump 20 feat and kill a guy with on hit in the head with your gun. But walking up to him and hitting him 20 times doesn't kill him..neither does a head shot? COD4 is way better IMO because I like realism. Also the detail of each level in cod4 highly surpasses Halo 3. Infinity Ward did a great job.