Here is the information about each character:

Minnie/Daisy: -Really easy to use when racing -Slow characters but with good handling -Terrible for speedrunning separate tracks(I wouldn't say they are terrible for speedrunning cups but if you do pick them you have a bad RNG since you left up Mickey/Donald which are the worst NPCs to face)

Mickey/Donald: -Jack of all trade characters -Can be used for speedrunning cups and/or separate tracks -Recommended for people who are just getting into speedrunning this game

Goofy/Pete: -The best characters in the game -REALLY fast but hard to handle, drifts easily -Recommended for people who have experience with the game's mechanics -Best characters to use for any type of speedrunning in the game