Ok, I see an important issue that answers a question poised by the creator of this thread hasn't been brought forth yet. Dick size has almost nothing to do with the type of underwear you wear. It's all about how comfortable you are, and how much support you need for youe testicles. This hang lower than the penis, and it can be quite uncomfortable if you have big or low hanging testicles to have them jostling around in bozers when you walk, or to accidentally sit on them. Pouched briefs provide the support most men need to keep the testicles up, so you don't accidentally sit on them, and so they aren't jostled around when walking.
I myself wear boxer briefs for the support because of my big balls. Before puberty, I wore boxers. My dad is the same exact way.