Popped my Diddy Kong Racing in about 6 months ago to see how it held up.
It doesn't.
The gameplay in Mario Kart is way better. The racing in DKR feels clunky. I realized the main reason I liked DKR back in the day was because it had a single player campaign and a lot of secrets to find. I still respect it for those qualities, but it is not a better racing game than Mario Kart.