This is very simple, but I wonder if there's a correlation between our fetishism and lack of interest in (or at least need for) hardcore porn. I saw Indy mention not even being into it, and it struck me that I'm not either, it just happens to be a means of checking out breasts in action.
So please, vote breasts only if it is the single most important quality of material that you find arousing. Consider option 2 to be a catchall for general eroticism, atmosphere, plot, sounds, anything else... and feel free to change your vote if you didn't read it that way the first time.