I have to give the win to Reach. Co-op campaign and great multiplayer both local and online. Second pick would be the first MW it had great co-op and multiplayer as well. Then I must say Black Opts just because its multiplayer is better then MW2, though campaign in MW2 is better then Black Ops in my opinion!

Reach is the most fun game ive played out of these

MW2 because it's the only one in which sniping rocks!!!

call of duty World at War was my fav but since its not up there but black ops is i am going to pick modern warfare because since world at war the series has gone downhill nice and fast in the quality department, yet its sales have gone the other way. I guess i am just an hater then :D

MW1: A really great single player campaign, with great mutlplayer to boot

MW2: Single player wasn't bad but comparing it to MW1 shows its flaws. Multiplayer had some great improvements, some great maps, some major issues, some terrible maps...

Black Ops: Single player is terrible, not even worth the effort it takes to play it. Multiplayer fixes a number of the major issues with MW2's balancing but is hampered by worse performance (PS3) and worse maps overall. However it does have Zombies...

Reach: An amazing single player campaign, well not setting a standard of story telling really creates the perfect atmosphere. Multiplayer is pretty great but doesn't really appeal to me on the same level as COD

I don't know...I think I'll give it to MW2 since I played it the most and it has Terminal my favourite multiplayer map

Reach 'cause Warthogs

Guys, stop including World at War or Killzone 2. I have added Halo 3 because some people wanted me too.

This is how I rank the games you listed

1. COD4 (The best COD IMHO)

2. Halo 3 (COD4 barely edges it in my book)

3. MW2 (Fucking ridiculous, but it is fun)

4. Black OPs (A little burned out on these by now, but nothing really wrong with the game)

5. Halo Reach (THIS FUCKING FRIED RICE STINKS!)

lol at KZ2

MW2 for me. Played the hell out of it.

Halo 3 for me, but COD4 is a close second :)