1.) Call of Duty 4 2.) Call of Duty 2 3.) Black Ops 2 4.) Black Ops 5.) World at War 6.) Modern Warfare 2 7.) Modern Warfare 3
.....somewhere in an alternate universe is Call of Duty 3. I enjoyed Call of Duty 2's campaign but the online was lacking. But still, I spent a lot of time on it and enjoyed it. Black Ops 2 would be tied for first to be honest if Treyarch could just fix it's lag issues.
I didn't rank WaW because I never played it online, only locally. I really loved MW2, even with all its faults, and I logged too much time into it. I played a lot of the first Black Ops too, but I realized I really didn't like it.
1. Black Ops: Nice maps with little headglitching. Interesting, if somewhat unbalanced weapon set (only the Ak74U and AK47 are in my boring bag). Probably the friendliest to starters in terms of unlocks, though with stupid pro perk requirements.
2. CoD4: Decent maps, and a fairly balanced weapon set. Many small annoyances like Matyrdom and the Frags.
3. BOII: Has a lot of promise and it is fun when it works, but the lag comp, too many headglitch spots and wonky unlocking bring it down.
4. WaW: Like CoD4 with many improved elements (sane grenade strength which also nerfed Matyrdom) and bigger maps, but ruined by the godmode MP40+ Juggernaut combo as well as Bouncing Betties.
5. Modern Warfare 2: The most interesting weapon set in the series with loads of interesting way to build classes, which fell on the fact that there many annoyances like the Nuke destroying objective mode, Commando, Deathstreaks, unlimited Claymore spam as well as some more grevious errors like the OMA/DC combination, killstreak chaining that was way too effective and so forth.
6. Modern Warfare 3: It has most of the downsides of MW2 aside from OMA/DC while inserting even more garbage in coordination with hopeless maps.