…And I've played every single one of them DURING their release window.
This does put me at risk of sounding a little bit "elitist" or "dismissive", but I do believe it's a point that's commonly overlooked when people rate other games in the franchise higher than COD4.
I've spoken to quite a few people over the years who are stubborn in their belief that MW2 and BO2 are both better games than COD4 (Which i'm fine with – we all have the right to an opinion),
But when you ask them what their first title was, they will say MW2 or BO2 more often than not. These individuals have then gone BACK to play COD4 for the first time AFTER they've played the COD4 sequels/successors first, when the technology had already improved and the franchise had already started to evolve.
But to truly understand the impact COD4 had, you really did have to be there in 2007 when it was the "current" game.
MW2 and BO2 are "refinements" of the groundwork that COD4 put in place. The Perk system, the Killstreaks, the "All Ghillied Up" mission, these things were unheard of at the time, and revolutionised the entire FPS genre. People literally stared at their screens in disbelief at the photo-realism of Chernobyl, and people were amazed by the addictive nature of the Multiplayer.
COD4 existed without MW2 and BO2, but if we flipped the switch, mw2 and BO2 never could have existed in the same capacity without the COD4 DNA running so storngly through them.
For that reason, my personal belief is that it's almost criminal to rate either of those 2 games higher than COD4. 95% of the code that you interact with is literally COD4 when you play any of those 2 games.