The interesting thing about Mario Kart is that I've played every single iteration, yet, it doesn't resonate as one of my top gaming experiences despite always being there.
SNES - absolutely ground breaking. I remember playing every cup and tons of multiplayer, but it was so long ago, I dont remember if it was friends or family.
N64 - this was all my High School and College friends. Late nights with a case of Miller Lite. Toss in some Conker's and Turok. Epic evening memories.
The DS and WiiU are where I remember playing with folks from this Forum. Some good memories of the WiiU tournaments, though I never learned the elite skills to abuse in MK8. The DS very was so popular at one point, I could open up ad hoc while on a plane, and typically find a few people.
I also think the DS had some of my favorite new tracks.
I've played some Switch MK8 while on Planes as well, but that was mostly destroying some friends.
I'm good at Mario Kart, but I'm not at the point of online-competitive, and i've never felt the need to be either. The later games have a lot more of that, which is probably why I've played my Switch mostly local. Just exploring the new tracks is fun enough these days. I can't be bothered to learn every shortcut, and which kart configuration is currently overpowered.
I'll add, I think a lot people missed out on Mario Kart Live Circuit. Those little Karts can run for along time on a charge, and it's not just a normal track. They added all sorts of really cool AR effects to the levels. Artificial wind, tubes, obstacles.... It's way more engaging than you'd think. It helps that I have a massive hardwood living room, but I've set up a simple oval track, and it's still engaging. I wish they put a stronger antenna in there for longer range, that would be my only gripe.