The problem with most 'penis size surveys' is that the lengths are self supplied. The average length accumulated from self supplied measurements has been found almost 1" larger than medical recordings in with doctors measure both stretched lengths and chemically produced erections. And being a man, I know my sensitive nature when it comes to penile competitions, and can easily see why many men would exaggerate somewhat.

Most girls I've spoken to/heard say that between 7 1/2 to 8" is best, but the 'vineyard' average is around 6 inches, while the medically recorded average was about 5.3". It's weird I know this, but being, if anything, underendowed, it was one of those areas I felt inclined to look into.