i like both games but i realy thing halo 3 is way over rated i mean its good it has nice online but everyone is like halo 3 is the best game ever and honestly i dont thing halo 3 is that great thats why i would chose cod4.
Call Of Duty 4, its much better grafics, online, campaign etc. You can accually start on a new "restige" if you do it bad in halo? what are you gonna do ? :S
i would have to say CoD4 just for the realism factor... the weapons and maps are obviously not a fantasy, which is preferable in my opinion. also, CoD4 is more versatile, and isnt a one console game (id rather not buy a 360 just to play it) for those of you who feel the same way, but still like halo, try unreal tournament 3... similar concept of the fantasy shooter, and its on the ps3!
CoD4 is the most realistic shooter out there, while Halo3 is just for fun and stuff. I personally think that CoD4 has better multiplayer stuff for the PC, but H3 owns it up on the 360
halo is more one of the games i would play for fun (for things like forge and co-op oops i think i just stabbed you accidentally hehe) but COD4 definitly to me has more replay ability online thanks to the prestige system.