Mario Kart 8 by a long mile.

Thinking about it, I came up with a bit more to the topic. While the point stands, that MK8 is the most accomplished Kart Racer, there were some Racers that were quite fun and were going in another direction.

A friend of mine is a Sonic fan and got a Sonic collection on one console (probably Wii). I am not a Sonic fan, but on game was particularly fun for me:

Sonic R is not really a Kart racer in the sense (obviously missing the Karts). But for me gameplay is quite similar to a Kart Racer and it is a lot of fun. The sense of speed feels just right.

Another thing missing these days is MicroMachines:

Also not exactly a Kart racer. But it was great fun to race about desks and in multiplayer the way you lose by falling out of the screen was great.

Wow someone knows the game!!!  Loved the game aswell. Did so many things right ^^'.   

I think the remastered CTR will be my favourite kart racer, they added so many extra things and even the costumes look amazing.

Not sure about the best, but my favourties were Double Dash and Mickey's Speedway USA. These days kids want to play MK8 most of the times, so that's mostly what we play (good game, though I dislike some of its tracks that swirl too much and really hate friendly fire in team multiplayer).

Diddy Kong Racing, it was leagues ahead of MK64 IMO.
A personal favourite of mine is South Park Rally, the Dreamcast version. I'm actually replaying it at the moment and its still great.

But MK8D takes the crown followed closely by Sonic & All Stars Racing Transformed.

Sonic and All Stars Racing Transformed! It is my favourite racing game ever! The speed is great, the controls, drifting feels so much better than in any Mario Kart. I prefer the roster as well in Sonic. The music is also so great. The main campaign is so much fun to play either solo or with friends. I'd honestly still be playing it if there was a port for Switch, as I don't fire up the Wii U these days. I'm hoping Team Sonic Racing is a good follow up, though I do not expect it to match SRT

Mario Kart 7 was my favourite Kart game on the 3DS.
Followed by Mario Kart 64 and than Double Dash.

My favorite kart racer: Crash Team Racing
The best kart racer: Mario Kart 8
best kart racer in a months time : Crash Team Racing Nitro Fueled???

Crash Team Racing is my favorite game of all time, but I'm lucid enough to realise it's not the best game of all time. Nitro Fueled will probably beat MK8 for me though when it comes out and fixes most of the problems CTR has (due to age) with AI in 4 player splitscreen, online multiplayer, customisable characters/vehicles and more tracks.

my choice too.

Probably MK8 but there should be serious competition by the end of the year with Crash Team Racing and that new Sonic racing game.