For some reason, I find a smaller dick on a well built guy VERY hot! Big turn on. Maybe it is the contrast to having a very well built body against a smaller member.
BUT, I also like guys with big ones. I like them all. So I guess I don't really have a preference.
I have been told by some men that they prefer to bottom for a guy with a bigger one. Otherwise it is like being poked.
For me the body and the face is the turn on, in additon to a hard dick.
A big dick on an out-of-shape guy or a face I am not attracted to is not going to get me into his bed.