Best Super Mario World
Worst Super Mario Galaxy for being linear and unoriginal.

Best Super mario world

Worst Mario tennis

Best = world

worst (that Ive played) = 2

Best: Galaxy
Worst: Mario is Missing

Galaxy or 64 for best, too hard of a decision.
Bad Mario Game? You said Sunshine. No, that was fun. Bad Mario Game would be Mario teaches Typing.

Best: Three-way-tie between Paper Mario: Thousand Year Door, Super Mario Advanced 4 (enhanced remake of SMB 3), and Super Mario Galaxy. Also, I would include Super Mario Allstars although that's just a compilation of 4 games.

Worst: Probably Mario is Missing, although it really wasn't that bad. SMB2: Lost Levels also wasn't my cup of tea just because of how long it took me to beat it :'(

Plus don't know what you're talking about.. Sunshine was great.  So were Super Mario Land's 1, 2, and 3: some of the late Yokoi's best work (RIP).

Lost Level was the super Mario Bros 2 of Japan and he was so pain in the ***...

Best: NSMB. All the awesomeness of all the 2D Mario put into one game.

Worst: Lost Level. It added little in term of gameplay, it was SMB but with different level design, no matter all the hate that SMB 2 get(why?), it added many new gameplay element which without SMB3 would never have been what it was.

BEST: Mario 64
WORST: Hotel Mario?

Best - Mario Galaxy and Super Mario Brothers 3 TIE
Worst- Super Mario 2 by far