do guys really care about boob size more than everything else?

Small to medium and natural .

Personality is # 1 , boobs are nice as long as they are not to big .

The smaller, the sexier

I've always been more of an ass man. But a few ladies over the years have had major tits. And I must admit, I would indulge in them. A female coworker would let me come to her place and for a few chores she needed done from time to time, she would have sex with me. I always fucked her from behind with her facing the mirror so I could watch the show. They were so big that even in doggy position, her nipples were into the mattress. They didn't flop, rather a roll went down them. After a few years, she had them reduced and she still sported a set of DDs.

I prefer the “looks” of a woman which includes both the physical and mental with no set standard nor preference with regard to size of any body part.

Boob size doesn't matter to me. I'm more into proportion, firmness and uplifted. I'm actually an ass man.

Where does the OP even get the idea that we care about that “more than anything else?”

Oh yeah, because society tells her that we do. Guess what! IRL, guys (at least with any level of maturity) don't in general care about appearance as much as women are led to believe we do. The so-called “beauty” industry leads women to spend inordinate amounts of energy worrying about their looks (as evidenced by this thread’s very existence) while draining nearly half a dollars out of their pockets, contributing mightily to women’s lower standard of living globally.

I’m not saying there’s something wrong with trying to look nice, but too many women are led to become insecure about their looks and focus on it way too much.

Sure, when a big-boobed woman walks by, guys tend to notice. But in an actual relationship and actual sex, most guys don't care that much. i've known a number of guys, even horndogs always who regularly brag about their "conquests," who still professed "more than a handful is wasted" or even "more than a handful is too much."

Run what you brung.

Nothing worse than saggy udders 😨

Short answer: the bigger the better to DD. Bigger than that isn't often aesthetic, form is lost to immensity and sag.

But it's not the only feature or the most important, wide hips is prerequisite.

I've always been more of a legs and ass man. Don't get me wrong, I love a woman's boobs, I just don't give a shit how big (or small) they are.

I love all sizes, so larger is not necessarily better. The total package is what I appreciate. A heavy woman with a great personality is better than a gorgeous woman with two rocks rattling around in her skull.