I in general notice proportions of people, especially those I'm intimate with. I find the look of penis, vulva, and testes something I'm extremely ambivalent about. In and of themselves I don't find testicles sexy. I don't feel there's any bearing between how masculine a man is or not in relation to them either. There was an incredibly attractive man I had a thing for at one point and he only had one testicle, due to cancer.
Purely visually I find the super saggy/droopy testicles more unappealing than those that are held closer to the body. And if a man wants me putting my mouth on them, they had best be shaved, waxed, or have the hair closely clipped.
Other aspects, I don't give a fuck about them. If a partner enjoys them played with, I'm GGG about it. I don't have a preference because they don't really matter to me.