Before I had even had sex, I knew masturbation would always be superior…
With a partner (even one I love/care deeply about), I rarely feel pleasure and feel a lot of pain and discomfort (ANY kind of sex, not just intercourse…actually intercourse tends to hurt the least). And even when I do feel pleasure, by body punishes me with debilitating pain. On my own, I rarely have discomfort and I can actually orgasm.
But you know what? I really don't think women are supposed to enjoy sex while men are. But, if I were a guy, I'd probably prefer masturbation because I can't imagine putting a girl through what I've been through for my own pleasure.