I’ve asked my guys friends this before.
I think (generally) they prefer shorter skirts.
(That isn’t to say that they all preferred mini skirts.)
For the most part, they also liked long skirts.
Because, as they put it, it was still easy access.
The exceptions to this were: the dirty hippie look
or anything that made you look like you lived on a commune.
NOTE: Probably got these answers while we were out drinking and probably a bit drunk.