I never played MGS4 so I won't comment on it, but I'll take everyone on earths word that it sucked.
MGS1: I played the fuck out of the demo of this, and it was the first time my decade-older brother saw me playing anything that he was actually into. He bought it on release day, and we played the shit like lunatics. The story is out there, but somehow even with an inhumanly emaciated psychic and a crazy Hulk clone surviving a tank attacked by grenades only to get eaten by birds later, my immersion wasn't ruined. It's like, sure, we're going over the top here, but the cold war conspiracy angle was over the top but in line with the tone of the overall game
MGS2: Okay, this game is super fun and really pretty and all, but wait, what? Liquid's arm is on Ocelot now and it's controlling him? Whatever, let's move on. "Laugh and grow fat!" uh, okay. "This chick is bulletproof? Oh shit, why?!" Oh... magnetic field technology. "Immortal gay vampire? Fighting my other brother who is also the president? Nine billion metal gears at the end?!" At this point I realized this motherfucker was loonietunes, but the game was a lot of fun so whatever
MGS3: Oh, the first boss is a maniac covered in bees, the survival system is dope and hilarious, the villain is some straight-up B-movie video lunacy, and it's still really fun to play. Oh, you can beat The End by setting your clock forward? Why let me play through this multiple times, killing him with a sniper, then knocking him out with the sleepdart, then shaking him down for his tags and the Moss Camo and eventually knocking him out via stamina for the Mosin Nagent. Bet the last boss won't be as good as this! (it isn't, at all)