For me it depends on the person, and there build, and personality. I've seen some girls with no tits, and no ass that are hot as HELL! Ive seen perfect bodied (lots of tits, and ass) girls that are not attractive to me at all.
However, I seem to look at whatever stands out the most first.
Taylor Rain has no tits nor ass to speak of and she is incredibly popular in spite of that. I guess it's her gorgeous, cavernous pussy and asshole.:dunno: