@scottjenson I like this - I came across your post after repeatedly messing up an image search because navigating to a submenu is intolerant to diagonal mouse movement (one of the gems of the Mac UI that I’ve always appreciated). I kept selecting a colour preference instead of a size preference. Little touches in a UI go a long way.
Keeping the duration at 50 ms, I definitely prefer “Smooth" over “Fade” and “Classic”.
I can see how the graininess of Classic might appeal to some people – There's no ambiguity at all as to where the mouse is hovering – but personally I don't think anything is sacrificed with the Fade, and it definitely feels calmer 😊