I mostly play Daisy with Peach coming in at a close second. I never really pick characters based on their stats though, I don't care about that even though I do play at a high level. I just like Peach and Daisy. Sometimes I like to pick a random one that nobody uses like Baby Mario or somth
Usually Baby Rosalina, with all bike standard items. You don't need fancy wheels to still win, and I've noticed I do better with the same kart instead of trying to mix it up whenever I play.