Mario Kart and NSMB are pretty even I'd say as franchises. NSMB2 is quickly catching up to Mario Kart 7 for example.
3D Mario is definitely several notches below and then Zelda is a notch below 3D Mario.
Nintendo's biggest mistake with the Wii/DS era was not investing enough in sustainable new character properties during that generation.
Instead they banked almost entirely on things like Wii Sports/Fit/Party and Brain Training and Nintendogs ... franchises that likely have lost a lot (if not even all) of their appeal.
So basically there's nothing from Wii/DS eras that really helping Nintendo now in terms of being new, so they're stuck having to ride Mario for every problem they have because there's no other answer they can come up with quickly.
DKC is really the only other franchise besides 2D Mario that Nintendo revived to big numbers that they can now carry over to the Wii U/3DS.
