Conlicted between 1 & 2, decided to lean every so slightly towards two and topple into it's questionable embrace. Sons of Liberty is definitely the MGS that had it all, great stealth, characterisation up the wazoo, solid combat, an enimga with a riddle kind of story with some great twists, some of the most memorable boss battles ever, the hardest reply options known to man at the time. Still nothing has equalled Euro Extreme in MGS2 for sheer unequivicol unrelenting difficulty. I should really go back to it sometime, I did MGS1 not too long ago.
Not the say MGS3 and MGS4 aren't freaking EPIC games. MGS3 technically might be the best looking game on the PS2 and it definitely has the charactisation, environments and story down. Some of my favourite moments in gaming are from MGS3.
I have yet to play Peace Walker, to my considerable loss. I want to pick up a new PSP before I settle into it, maybe the Go since I'm looking for an MP3 player, and as long as I BUY the game on UMD, I see no reason not to arrange myself a less inflated digital copy.