Depends which Mario Kart; I would actually rank Crash Team Racing above many of them, such as Double Dash, 64, or SNES.

Mario Kart 8 though has Crash beat, and is the very best game in the kart racing subgenre made to date.

That said, CTR is an excellent game in its own right, and a worthy opponent. I'd say either that or Sonic Racing Transformed are the best MK rival ever made.

Mario Kart is way better. Mario Kart needs a proper story mode though.

I like Mario Kart, but CTR: Nitro Fueled is my favorite kart racer, so I will have to go with that.

I have very limited experience with Mario Kart, so my opinion isn't worth much, but based on my limited experience with Mario Kart, I'm just not feeling it. On the other hand, I absolutely love CTR, so my choice is really easy.

Mario Kart 8 is the best kart racing game ever.

If you compare the original CTR and MK64 however it's not even a contest, CTR the better game.

Mario kart, there's a reason it survived over other kart races. The reason is it's way better then most kart races on the market.

For me, Mario Kart 8 tops everything in gameplay, but the modes are severely lacking. Grand Prix and Time Trials for years on end.
Where are the challenges, boss races, story mode, open world hub, custom tracks, etc?

I thoroughly enjoyed the Crash Team Racing remake, there's just something about going through corners that's more enjoyable with Mario Kart 8.

Besides all that, Diddy Kong Racing is still the undisputed king of kart racers and it's a damn shame they never expanded on this foundation.

Booted up MK8, had a few races and it certainly does feel better, I get what people mean but Just some of the things that are going on under the hood and this is before diving into advanced player tricks for the remakes Hard mode. Spent some time on YouTube watching high level play and CTR looks to have the higher skill ceiling. There are just more mechanics and the obstacles in CTR add up to something that is more deep, I am aware that there is nuance to mk8 but it's about taking corners like a sim racer, It's all very straightforward. 

The above is very basic stuff. Watching some of the pto stuff compared to some of the pro MK8 stuff is pretty telling. Now which is more fun, 🤔... CTR is most certainly more frustrating. 

Original CTR is the best karting game I have ever played. However the sequels leave a lot to desire. Also the last CTR remake lacks soul. So Mario Kart Franchise is a better franchise but CTR is the best individual karting game.