[daniel2]

Big ones are nice, about the size of your clenched fist is really good.

[SharonValerii]

Larger breasts are more noticeable. (And males are genetically pre-disposed to, erm, notice.)

This doesn't mean they are preferable. There have been eras when non-sag non-bounce was considered the "in" thing.

Some guys go for boobies, some don't. IME "genki", upbeat attitude, and vivacious personality get more male attention that any one (or two or five) physical attribute(s).

For that matter, it's not so hard to play-up or play-down your features by altering your style of dress. I can think of several ways to either emphasize or downplay your cleavage.