It's funny how people dislike Raiden, I think Metal Gear Solid 2 was the best MGS game. I like how it was open ended, had tons of philosophy, and how it introduced the patriots.
I think if Snake was the main character in that one, the game would have been a lot worse. IMO, the game added to the coolness and maturity of Snake by having the blinded soldier be the main character. Snake was getting older, and was at a know-it-all stage, same with Otacon.
And in my opinion, the bosses have always been crazy. If anything, I'd say MGS2 has some of the most sane bosses of the series.
But anyway.. enough defending MGS2.

I love this series, and I dont think I could rank them outside of liking MGS2 the most. Here's my favorite Codec scene:
This part, and the part with the president are the most memorable parts of the series in my opinion. I'm a fan of enemies who think they're doing the right thing and being unselfish.. MGS has loads of them.