I'll try. I wouldn't count this as best to worst though. I love all of the games and it's hard to even rank them. With that said, let's see if I can do it...
Metal Gear Solid 2: I was one of the few that actually liked Raiden in this while everyone else was hating on him. Of course, this all changed after he turned into a cyborg. With that said, there is just something about the story and gameplay that I just enjoyed. Even moreso now that I am older and have finally made some sense out of everything.
Metal Gear Solid 3: Gameplay was much improved over 2 and the story was less convoluted and much more emotional when it came to certain things (The Boss being the major one).
Metal Gear Solid: First Metal Gear game I played. This game is what made me a fan. With that said, it is a bit dated now. Granted, I haven't played the original in a while and have only played The Twin Snakes recently (and I have my problems with it; the cutscenes being a big one). However, from what I have watched, it just looks like it would be hard to go back to.
Metal Gear Solid 4: More cutscenes than game. That said, I still like the game although it is the one Metal Gear game that I haven't gone back and played multiple times compared to the others. I did love the change in controls though.
Metal Gear Solid: Peace Walker: Got around to finally playing it because of the HD collection. Again, liked it, but didn't care much for the story and the boss fights. I understand it was originally on PSP but I thought they could have had some more memorable boss fights. Also, like 4, the controls are great. I also loved the base building aspects.
Metal Gear Rising: Revengeance: Great action game. Can't say much more since I do not remember too much about it (aside from the final boss being both awesome and a pain in the ass to fight). Plan on replaying this sometime soon.
I have not played Ground Zeroes (was going to play it whenever I get a PS4 or One) or the original Metal Gear games (not for lack of trying) so I will not say anything about them.