I don't mind competitive multiplayer, I don't even know them and I will probably never meet them. So who cares about them? When I'm playing online competitive with friends it's completely different because we always joke around.
However, I've always preferred co-op more than competitive; Resistance 2 co-op was heaps of fun for me, the Special Ops mode from MW2, Nazi Zombies in WaW and BO. I love playing all of these co-op games with friends, because online people will camp, noob tube and knife you from 5 metres away, AI, however, don't do this.