I enjoyed MGS2 a great deal, although go back and forth on it when I look back at it. I'm scared of MGS3: started the first level and the micro-management eating/hunting mechanic made me put it away as fast as possible. I can't stand stuff like that, I just can't. It's game-breaking for me, just like the one-save system in Dead Rising.
The message with MGS4 was that it'd scrub off some of the rough edges to reach beyond the hardcore fans: controls and obtrusive japanese complex design for the sake of complexity, super weird shit, cut scenes, codecs. But after playing MGO I don't have much faith in the controls and a polished/stream-lined interface. From reports cut scenes seem to be more, not less.
I really want to get into it.