if its for online play
gears of war is def the best one and the one that requires the most skill, its prolly the best game for sniping, only real problem is host advantage, but oh well in sniper games it doesnt make much difference

, also sometimes shotgun fights might turn out ridiculous, like u can get downed from so far 1 shot its not even funny, but overall its the best shooter
halo 3 comes next, its just some fast paced shooter, hale 2 maps were better tho, and i got bored fast of this game, i only like team snipers and team swat, which are the 2 modes ure going for the headshot, altho in this game grenades can be annoying, but in friendly matches u can have some good time, ranked is pretty much all about vehicules tho, which i hate, cos vehicules require no skill to use, so noobs just use them and get easy kills, also since spawns always change, u always get banged by everywhere, but oh well, i gues its meant to be this way, some fast paced action
and cod 4 comes last, this game sucks, all u will see there is ppl crouching in the grass, hiding, camping, never moving just keeping their spot and waiting for someone to pass in their crossairs, which were already set to where ppl will come from, ready to fire.... this game is just lame, every1 hides at his spot, doesnt move and waits for ppl to show up in their crossairs.... every1 says wow this game rocks its so realistic.... WHO FUCKING CARES its a game, its not real life, who cares if graphics arent realistic if the gameplay itself is better, anyway, pretty much anygame on 360 will have good graphics, but ppl seem to rely too much on graphics to pick a game, they want it to look like real life even if the gameplay is worth shit