Damn, each one is so good and innovative it's hard to pick.

Super Mario Bros. 3 followed closely by Super Mario World and Mario 64.

Runner Up: Sunshine - I loved that game.

Super Mario World, and Mario 64. Snowcatt's right about Mario 64 being very solid mechanically, but mostly I like that they make the obstacle courses feel like real places, where Mario 3 styled games make the obstacle courses feel like... obstacle courses (Mario 3 is closer than Mario 1, but when I think of Mario 3, I think of Pipe World and the way every castle is still made out of Mario 1 blocks and it just forces me to confront the fact that yup, it's just an obstacle course.)

Galaxy is probably my favourite of the obstacle course games, and again it may be because it feels more natural to me than NSMB even if it doesn't reach the natural feel of SMW.

Sunshine is the worst "semi-real places" game to me because of its faulty mechanics, but it's got charm.

I'm going to go with 64. I have some serious memories with Mario 3 and Mario Land (which is awful, but weirdly fun), but Mario 64 was probably the most consistent and enjoyable.

Super Mario Land 2: 6 Golden Coins is up there, though. That game rivals World in quality and charm.

I watched a speedrun the other day. Does that count? If not, I played though it again a few years ago and felt it still held up despite the Nintendo 64's joystick's proclivity for committing unspeakable atrocities on left thumbs everywhere.

Doki Doki Panic aka Super Mario Bros. 2.

I have fond memories of playing Super Mario Bros. and I played 3 and Super Mario World but, i dunno, it's just the odd one out I really liked.

I liked [url=http://en.wikipedia.org/wiki/Wrecking_Crew_(video_game)]Wrecking Crew[/url], too.

Donkey Kong. Best Mario game evar.

Is "Good God, man, none of them!" a choice?

Never played a Mario game. Actually, any of the big Nintendo franchises have I zero experience with.

semi recently as in 3 years ago
it still held up well back then

better then most other n64 games at least

Super Mario 64, no question. I like the sense of exploration you get from all four of the full-on 3D ones but 64 does it best. No weird gimmicks, no weird space theming, just straight up vanilla Mario awesomeness. If Galaxy suffered anywhere it was from not having enough worlds where you could run around and just plain explore like in Sunshine. Worlds were really linear in that one. The FLUDD pretty much killed Sunshine for me, otherwise I'd have liked that better than Galaxy.

The runner up would be Paper Mario: The Thousand Year Door. The first Paper Mario was good, but the second one just kicked everything up a notch. I haven't played the third one or that one with the stickers.

Super Mario 64

Side scroller: I actually really like the first one more then the third one.

3D: No competition really: Galaxy

i haven't play any mario games except on NES, (my next gaming rig is PC).

super mario bros 3 hit the sweet spot too.

Super Mario Bros. 3

No competition.
I'm currently playing the original NES version in multiplayer again and it's not only way ahead of it's time but still better than any other Mario game although Super Mario World 2 and Mario 64 were very good too.

It's quite tough really... my top picks would be Galaxy 2, Mario 64, Mario 3 and Super Mario World but picking a best one is hard.

But I'd probably go with 64 because it just got 3d right. I wish they'd do another Mario game with the same free roaming exexploring style as the latest ones have all been like 3d versions of the original 2d games.

I assume with "Super Mario Brothers" you mean the actual "Bros." series, i.e. Bros. 1 - 3 and World, right? The 3D ones are entirely different games, and so is Yoshi's Island (the Super Mario World 2 part of the title was added by the western marketing team).

My most-played one has to be the first Super Mario Bros., it hits the perfect spot between simplicity and richness. It is much faster and tighter than later Marion games, but it is still full of content. It is especially impressive when you compare it to other contemporary games which usually consisted of a few screens and just kept looping over when you beat them.