I loved MK Wii besides the horrible tethering system they put in. When I'm in first place because I can skillfully drive, then I get dead last because I get hit by 3 blue shells, 6 red shells, and lightning on the last lap, that's just downright bull****. And yes, that has happened to me before.
My favorite is still the original Super Mario Kart. I liked MK64 but I never owned it, and I didn't like the seperate items for Double Dash, although I still love the game. MKDS was amazing, probably my second favorite, but I never bothered learning how to snake, so playing online was pointless.