I have read many forums lately. What I noticed is a difference in preference in cock (sizes)…
The difference is in experience. I don’t have data… observation only.
What I see is for both women and men, the more sexually experienced they are, the bigger the cock preference is.
I also noticed that when they (men/women) go bigger, they don’t tend to go “back” to “smaller”.
Why is that? Do you recognize yourself in it?
I find it an interesting topic… 
Once again, this is purely my observation… 