Ranking from favorite to least favorite (please note I do like all these games, but some just have a downside);

1: MGS1. Smooth stealth action, amazing pacing, creepy and tense vibes, cool bosses, simple but very effective control scheme and game mechanics really made me feel like a professional infiltrator. It still is my third favorite game of all time. Such a blast.

2: MGS3. Again, awesome pacing. I really like how the setting changes after each few areas; there's so much variety, even in the jungle. Not to mention there's some pretty unique gameplay features not many games dare to set foot on, like being able to kill the End before the actual battle starts, or poisoning the Fear, scaring soldiers with the crocodile mask etc. On the downside: the cutscenes can be a little overboard, bosses like the Fear and the Pain are forgettable, I seriously dislike how they removed the 3rd person auto-aim which worked so well in the original MGS.

I also hold a grudge for this: there is a cutscene where Snake literally rips an Ocelot crew apart with all kinds of fancy moves. Very nifty, I thought. Let's see if I can do that with the actual gameplay. But no, that tit is impossible to pull off. The game doesn't fulfill the promise it made in the cutscene, and that is a shame. It makes me feel less like a professional infiltrator and more like a clumsy slowpoke. It's all about immersion, and those sort of cutscenes really take me out of the game.

3: MGS4. First time through I was blown away by this game, it does a lot of things right! Stealthy sneaky action in the midst of a battlefield? Ohyeah. Epic finale? Ohyeah. The return to (SPOILER)Shadow Moses? Ohyeah! But after playing through it last year I came across many flaws. The endless stream of enemy soldiers suddenly pouring out of annoyingly places spawn points, destroying the stealthy route you've been crawling towards for 15 minutes. The cutscenes are long. Very long. And I don't mind long cutscenes when there is a story to be told, but seriously, watching bosses scream and moan for 5 minutes is just plain boring. And then after multiple playthroughs the charm of the game went downhill; why can't I just walk to the end of act 3 if I already know where to go? Make a little easter egg out of it when you do? I never understood Naomi's motivation to double cross everyone. And my biggest issue of all: how the hell do all the good guys live? Raiden should've died while being crushed. Johnny and Meryl should have died fending off the FROGs. Snake should've killed himself. It's like this game had lost it's edge, it's guts to be radical, and therefor comes off as kinda anti-climatic. None of these things bothered me on first playthrough, but now they do. Bummer!

4: MGS2. I have a it mixed feelings about this one. I like it, the music is awesome, the ship is one of the greatest levels ever designed, I liked the freaky stuff going on at the end and even the ninja's and stuff felt like they belonged, even as surreal as the situation was. But I didn't like how they removed the 3rd person auto-aim. It was the beginning of the abandonment of the smooth high paced gameplay that made MGS1 great, and that is a shame.

Some lost potential:
I hated chasing those bombs around. I once read that the original plan was that Raiden would chase Rose around on the Big Shell, visiting each platform, but after not being able to find her and only having contact by codec, the player would start to doubt whether she was actually on the platform or if she exists at all. That would be much more canon with the whole AI theme, and would make for a much greater mindsmurf than just freeze some bombs here and there.