Super Smash Bros. It counts in my mind, at least. I've never been a big fan of Mario games, the only ones I really ever put any time into were the two "different" versions of "New Super Mario Bros." (on the DS and then on the Wii). I have always liked the Mario Kart games, though. Double Dash was my favorite in terms of mechanics, Wii is my favorite overall simply for the amount of content in it. So I guess if you won't count Super Smash Bros. Brawl/Melee, then it'd be Mario Kart Wii (of course, I always play as Bowser. . .)