I'll go with NES/SNES classics. More specifically, my real answer is Yoshi's Island, a game I consider to easily be the best 2D platformer and possibly best platformer of all time. I'm sure many will respond with "that's not a Mario game, that's a Yoshi game." To that I say, first of all, when it was originally released there was no Yoshi's Island series and it was dubbed Super Mario World 2. Secondly, at worst, it's a spinoff series, because Yoshi was introduced in Super Mario World (and Mario is riding his back throughout the whole game). It would be super ironic not to count a spinoff like Yoshi's Island in a forum that habitually lumps in all games with "Final Fantasy" in the name when considering or barring games from a topic and, as I noted above, Yoshi's Island did actually have Mario in the name.