Halo 2 > Halo 3 > Halo 3 ODST > Halo Reach > Halo CE
Based on campaigns.
I hate how 343 had to cater to the crying 3 year olds about friendly fire. Just take a joke, yknow, its different in competitive because its all about winning the match, but living dead is just for casual fun and you don't suffer from being betrayed, in fact you gain from it, you spawn with full ammo and it can potentially get you out of trouble. Me and my friends would often betray each other when zombies where about to kill us so we spawned somewhere else.
But oh well, whatyagonnado
[Edited on 02.29.2012 3:25 PM PST]