Black Ops. Hands down. That PoS Hackfest Infinity Ward released as their Swansong is a joke.
They never wanted to release it (in fact, IW announced that CoD4 was to be their LAST CoD game when they released it). Their publisher / owner FORCED them to do it (and it shows). We're coming up on 18 months after release, and they still haven't fixed all the issues from release day.
MW2 was a pure "Money, money, money and more money" release. Black Ops also has dedicated servers, which means that one of the people *in* the game (chosen at random) isn't hosting the game. The game also isn't playing on a P2P network, so you only have to worry about two datastreams - the one to and the one from the server, instead of 16 other datastreams for the 8 other players in MW2 Black Ops also had a full two year development cycle, not a 9 month one like MW2.
Good Luck!
Black Ops. More features, better graphics, better connections (especially for zombies), dedicated servers, and more customizable (and record-able) features. The only negative may be the weapons; they're good, mind you, but you're limited on what can go in the secondaries (mostly pistols, crossbow, and smgs) as opposed to MW2.
Plus, MW2 has a bigger library of weapons (I think).
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.