I never played the first Super Mario Kart until I got the WiiU, having been a big fan of those games, I was happy to finally play the first... And it wasn't as great as the others. It's still a good game, but I guess the later games were so much better that it's hard to rank it as one of the best (maybe an example of TV Tropes' "Seinfeld is Unfunny"). I did want to play the game when it was new but I didn't have a Super Nintendo and not many people I would visit had one (we all seemed to have either an NES or a Sega Genesis).
On the other hand, a few years ago, I played Mario Kart 64 (the first of them I ever played) for the first time in a long time, and I feel like that's still a great game. The most recent ones (Mario Kart 7, Mario Kart 8, Mario Kart Wii) are also super great.
The only Mario Kart console game I have not played is the one for the Game Cube.... And I didn't even realize until a few years ago that my brother had the game (I don't even remember knowing about the games existence back when it was new) but he seems to have lost his copy. Of course while me and my brother had a Game Cube I didn't really play it very often (there weren't many games I was interested in). Otherwise, the only other MK games I have not played are some of the arcade games (but my local Chuck E. Cheese used to have the second one; I thought it was fun but not as good as the other ones, despite also including Pac-Man characters).
It's interesting how at first, most of the Mario Kart games incorporated the system name into the title (the first arguably counts, as it's the only one with "Super" in the title, but "Super" is a common term in the Mario games, and while it was in many Super Nintendo titles, I don't know if Nintendo planned at the time to make more Mario Kart games, not to mention they dropped the "Super" from the series after the Super Nintendo had been discontinued anyway), and yet the last couple of them have sequel numbers in the title.... And those two came after they started producing the licensed arcade games, and therefore are not really Mario Kart 7 and 8.