PB's right; it really depends on the guy. Me, yeah, I like decent-sized T's, and no, I couldn't explain to you why, other than they're something to play with, sensitive, sensation spots? Heck if I know. What other things do I look for...soft skin would be the only universal thing, really, because there's something that overshadows all of the rest:
The girl's gotta have an overall beauty.
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Some might find her unattractive. May be too flat, hair's stupid, too tall, whatever. But for me, she's GREAT.
You could find a woman with THE PERFECT BODY, but what if it's attached to a face that makes babies cry and a personality to match?
Suddenly, the allure is ruined. There has to be a balance, every trait has to have some minimal level of quality; overall beauty.
[spoiler]And as a fair-deal guy, I'm trying to live up to the same standard, but I can't workout because of the College from Hell and my face and hair need lotsa work.[/spoiler]