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.