Mario Kart 64 was the first game I ever played in my life. I know it has its bugs, but man the execution is there in the driving aspect, drifting, and race tracks/music being incredibly memorable. That being said I have to say that 64 was the best MK game made. Not because of nostalgia, but because of execution, and the feeling of each character having unique perks. Toad is fast yet light and actually does go flying fairly far if crashed into at high speeds. If you approach Bowser and hit him from behind there's a great chance his shell spikes will spin you out. Mario is balanced and in a lot of cases it's difficult to overtake him because of his all-around stats, and etc. I will be honest, the items do seem clunky, but hey they can still be used. It's just impossible to use red/blue shells on Rainbow Road because they keep running into the walls, though. And while it is easy for people to pick up it still has an aspect that there's a lot of driving techniques and drifting to be perfected, which kept me playing for hours on end just to perfect that one ramp on Koopa Troopa Beach (those who played the game, yes you know which one I'm talking about). Yoshi is pretty OP in this game though.

Second best game is Double Dash.
entertainment.net wrote:I do really like the mechanic of having two items at once. I especially liked being able to switch drivers right before hitting an item box and getting an additional item when you only have one.
Also the first Mario Kart game to have unlockable characters. Toaaaad <3
But yeah, DD had great music, Baby Park, very fun battle modes (which I barely played since I'm so lonely), and I once hoped for MKWii they would've made it triple dash or something, lel.
Third is MK7. I haven't played 8 so I can't really compare it to 7 or anything but 7 kept me on the hook for a while. Really nice item display, interesting character and kart customization mechanic (brings me back to the days of MKDS), and nice track selection. Oh, and great music. Drifting Mechanic works great.
Honorable Mention is DS. This game I probably played the second most after MK64. Sure, it had its problems like the abusiveness of snaking and some aesthetics were missing (like no flames coming out of the karts when you turbo drift), but man was it a fun game. Missions were a nice touch, VS I probably spent the most time on, and yeah.
Everything else comes after. But hey, with each MK being unique (although I will say Super Circuit is not exactly the best, I played it a lot but meeh), they're still all great games.