I love most Mario Games, but definately hate some of the spinoffs and hate Super Mario Brothers 2 (which wasn't a real Mario game as we all know).. but SMB1, SMB3, Super Mario World, Super Mario 64, New Super Mario Brothers, and Super Mario Galaxy are some of my favorite platformers ever made. I have to say the Lost Levels (the real SMB2) was alright too when we got it on Super Mario All Stars. Aside from those core platfomers.. I thought the Super Mario Land series was .. okay, but not as good as the real core platformers.
Aside from that I like Mario Kart series, and if I'm drunk and with irl friends, Mario Party isn't bad either (in fact it can be rather hilarious on the Wii version).
I think Mario's face gets abused on too many products though. Mario playing sports.. ... eh.. no.
But give me another game like Super Mario Galaxy and hell yes I'll love it. One of the key enjoyment factors of Super Mario platformers vs a lot of other platformers is the sheer amount of variety in them from Super Mario Brothers 3 and on, they got into different worlds, with unique powerups that might only be found on 1 level, which I think is cool, keeps the game from getting stale.
Between Mario and Megaman you have my 2 favorite platformer series right there.