I fish the rivers heading into Lake Michigan and from what I see, I don’t think the color is that big a deal, but you don’t want too big of a float. You want one that just barely holds the bait at the right depth. You want to see it twitch when a fish hits, but also, those many times when a hit isn’t obvious, you don’t want that big bobber suddenly dragging on the fish as the current pulls it downstream.
It doesn’t hurt if you can change the depth easily as well. Sometimes they want it higher or lower and the pools can be different but bobbers work great, which is why so many use them.