I did get ftm top surgery a while ago so currently I'm flat. But as my mind would have it, that was not a good decision on my part. So I'm now looking into getting a new pair reconstructed. The upside of that is, I'll get to choose my boob size, within reason of course.
Ideally I'd like something like a D- or DD-cup (so I voted both of those) but I'd be okay with a C if bigger would be difficult for a surgeon to stretch my skin to. I'm average weight and have a kind of small frame, however I have the widest hips and biggest bum ever, so I think a bigger bust would balance that well. Also I have quite wide shoulders so bigger boobs don't look weird on my small ribcage, in my opinion, but rather just right. It might seem very big, but I've really never been much for moderation. I'm a "go big or go home" -kinda gal.
I currently wear breast forms that fit my 32D bras, and that is a size that's mentally comfortable for me. I wouldn't mind slightly bigger, but no way I'm buying new breast forms just for that. And yeah 32 (70 in eu) in band size seems to be what works best for me.
My original boobs were B-cups. In moments when I was not dysphoric about them back then, I did actualy like them but thought they were too small. Pre-transition I often wore them in push-up bras with lots of extra padding, so they looked like C- or D-cups.