Which do men prefer: strangers or friends/partners in bed?

I like sex period. Is it better with someone I know. Sure. But there is also another factor involved here. It is not commitment-phobia, it is emotional phobia. Most guys would like to just have sex for sex sake. A release if you will. With a stranger, there is no emotional investment needed. With a partner (a week or a lifetime), you can occasionally have sex for just that - sex. But typically, you have to invest some emotion into the equation and most of the time, most men don't want to have to do that just to get off. Hence our fascination with masturbation. It obviously isn't the same as sex with a partner, but it achieves the same goal - a release.