I enjoyed the most (and replayed many times): Super Mario Bros. 3 on NES and Super Mario World on Super NES.

For me it's Super Mario Bros. 3. Fantastic levels, gameplay and music! =)

For me it's a tie between Super Mario Bros 1 and Super Mario World.

For me, it would be Super Mario Bros. 2 the USA version, not the Lost Levels. I loved it, because it was different formula, instead of pipes and Bowser, new enemies, worlds, and the vegetable pick up was fun. The music was different, and I loved playing as Princess Toadstool (Peach) and Toad.

I played nearly every Mario game up till the first 3DS game 3D Land and the first Mario game I was ever introduced to is 64 (I am pretty sure I have played before but 64 is the only one I remember). But honestly:

Super Mario Galaxy 1 and 2 is perfect. it always makes me smile and get teary-eyed with its orchestral soundtrack:

https://www.youtube.com/watch?v=VEIWhy-urqM

https://www.youtube.com/watch?v=xsyPHkeyz6o

Super Mario World. The perfect Mario game IMO. Levels,music,graphics and gameplay are all flawless.

It is going to be hard to top Super Mario Galaxy 1/2, because I love those titles too! Super Mario Sunshine was a great different locale to explore, even though the 120 shines was 120 stars from Mario 64, and too many coin missions and blue coin collecting!

Mario 64 is one of the mario I have very fond memories of, but for that same reason I wouldn't dare power it up again. The thought of it is making me anxious. I am glad I fully completed it years ago.

The thing with the marios, is that the musical score is getting more impressive with each new game. I loved Galaxy for that more than the gameplay (but I really enjoyed the gameplay nonetheless : one of the richest among every game ever made)

My two favorites are New Super Mario Brothers.wii and Paper Mario

:)

https://www.youtube.com/watch?v=KYhmHovdBxY

https://www.youtube.com/watch?v=9UYXABAC06s

For me it would be Super Mario Bros. 3 but it could be because of nostalgia, also didn't play any recent one.

Top spot goes to Super Mario Bros. 3. I like it the best and it plays best to me. I also like the level design just barely more than Super Mario World.

For the 3D games... It's hard to say, I like most all of them a lot, although I'll admit I think of Sunshine, 3D Land, and 3D World as about as good, even if in different ways, whereas 64 is interesting and good but not great. I also consider Super Mario Galaxy very good, but not as good as the first ones listed and Super Mario Galaxy 2 is not quite as good as the first one to me.

If I had to pick one favorite, it would definitely be Super Mario Bros. 3.

Super Mario Bros 3, Super Mario World and Yoshi's Island. If I had to pick one, I'd go with nostalgia and pick World.

The 3D games didn't do much to me. SM64 was great for its time, but nowadays too many things annoy me (including the so called perfect camera *ahem*). Sunshine went too far with the SM64 formula, I'd rather have more levels than collect a bunch of stars on the same ones over and over and over and over and... SMG1 was an improvement over SMS, but it way too easy and the levels barely had any platforming action. SM3DW, kinda like the New series, was blast playing in coop, but a snoozefest when playing alone, it was even easier than Galaxy (not counting Champion's Road).

And for all the praise Galaxy gets over its soundtrack, I actually prefer 3D World's soundtrack as a whole.

Yes that.
I was also thinking of that level where you ride a ball and the music plays according to your speed. That's the pinacle of my gaming experience. Because you can beat the level, or you can beat it with fashion and bling. Extremely rewarding.