Double Dash > 64 > Super Circuit > 7 > DS > 8 > Wii > Super
For Mario Kart I personally favor local multiplayer over online, so that's why Double Dash and 64 are highest. Super Circuit is underrated imo, it's got a steeper learning curve than the rest but it feels so satisfying to get good at drifting, and the tracks are great. 7 has amazingly tight control. I have great memories of playing DS with friends, but I don't like the controls as much and snaking killed the online for me. 8 always felt really stiff for me in terms of control, and both 8 and Wii feel kind of barren unless you're playing online with 12 real people, as that's how they were balanced to be played. I like Super, but it's last for me since it's only 2 player and Super Circuit is basically the same thing but better in most ways for me.
While I definitely like some more than others, I do really love all of them though. I have nostalgia and fond memories for every single game in the series.
EDIT: I forgot Mario Kart Tour. I don't like it at all. Even excluding the tons of micro transactions, it just feels watered down compared to the others. I gave it another chance when the multiplayer beta went public and my opinion stayed the same.
