Size doesn’t matter, the saying goes. Just as looks are not important.
Yes, probably. Ultimately both things are true. And it is true that looks and size are less important than more spiritual qualities. And it is true they matter little when you’re in love.
But I find that for immediate attraction and for fantasies, looks and size are all important. I am not going to have sex fantasies about a old, ugly man with a tiny dick, am I?
OK, when fantasizing about girls, I like both small and big tits. But you don’t insert those anywhere, so that’s different. 
Have you seen those fine art drawings with a man or a satyr or whatever, with a cock almost as big as he is himself? I think those are really sexy. I am not sure why I think so, for you’ll never see it in real life, and if you did, you couldn’t insert it anywhere… But fantasy does not have to be logical, I guess.
