So in real life there is such a thing as a too big cock, also such a thing as a too small one, but the latter varies with what else the owner of said cock does, not necessarily with the cock, but with his mind and body

What a big cock can give if used carefully is very quickly hitting all the pleasure areas inside and also there is something about fullness, that is why some enjoy something like fisting, I think it triggers some things that you otherwise would normally only get while giving birth, human cocks don't really compete with fist sized things though, and also there is one further factor, the size/tightness/and how stretchy the vagina is, or other place the cock is going, some like the challenge of taking something stupidly big, some women can like their cervix being repeatedly hit by a cock (not too hard though), others just can't, there are also women with certain mental or medical conditions where they would need a tiny cock, as anything bigger will hurt, no matter what they do, and maybe no cock can work without pain.
In my fantasy stories my female characters tend to be enhanced by magic, so they can take a cock with a cock head larger than their head without injury, as they stretch, I do that partially for silliness but also the size difference is interesting, and I can imagine the intensity, and like that kind of thing at least in stories.
For breasts and butts I like a combination that looks good as a whole on the whole body, I do not like tiny or huge breasts or butts relative to body, but I do like curvy also I like enough fat on female characters that when she is not flexing her muscles they don't show, but if she flexes they do show, but not all veiny and stuff, that may sometimes look good on men, but I also like men with some smoothing and less veins.
Also I am silly with the males, sometimes I love the idea of an impractically big cock on a small male, so much so that you know if it is fully erect there is barely any blood anywhere else in his body, and his brain is on emergency life support and not thinking at all, in real life that would not work, the person would faint and fail to operate his cock.
I think this probably makes me a bit boring though, but perhaps not exactly in the common hotspot for porn, but close to it on some axies
