Have scanned over this thread, which stretches back to 2012. My opinion is that the 'average' women prefers an 'average' size cock. Shouldn't be any particular surprises there. There will be outliers at both ends of the spectrum of course, with some preferring smaller and some preferring much much bigger.
The thing is, if you look at this across large periods of time and assume given enough time, that sexual selection would eventually work its way through as as form of Darwinian natural selection, then, a lot of we men would be sporting 10" wangs, and the 'average' would therefore likely be 8" or so. We'd still be having the same conversation probably
At the same time, and using the same thinking, men obviously prefer average size vagina's ... otherwise we'd all be in a real pickle. Imagine 100 generations from now with women all having tiny tiny pussies and the men all flopping about with giant penises that can't comfortably and pleasurably 'fit' with the average woman.