Loved MGS, especially MGS3. Peace Walker... meh, somehow the story and characters just weren't appealing to me.
MGS2 was nice too.
I'm wondering what Konami is going to do with the MGS series, since I heard they would continue it. I dunno, it could be good. Quite frankly, I didn't like Peace Walker, didn't like anything about its story, and Ground Zeroes seems a bit too serious and 'western' for my tastes. I dunno, it just didn't feel quite right. Metal Gear Solid was always about planning and taking advantage of the environment, but I found that lacking in Ground Zeroes. Plenty of times I would just bump into a guard that was randomly patrolling far away from where he was supposed to be, and had no patrolling 'pattern'. Meh, Kojima wanted to quit the series with MGS4, I think he's had enough involvement with it.
I'm more interested in Metal Gear Rising at the moment. It was already a pretty awesome game, you could actually do quite some nice combos, and the presentation (soundtrack, visuals) was great. Heck, I even appreciated its simple story, even though the acting was pretty subpar sometimes.
Don't know what Kojima's plans are now. Maybe he can start his own development studio... it would only make his games better, no doubt.