I usually go commando, except while working. I've worn boxers for a very long time, but I've always hated how the legs crumple and ride up..I tried some gripper trunks from CK, which are very comfortable, but the legs also ride up a bit when them. So I decided to try briefs again.
I've got some CK microfiber hip briefs and I really like them! They feel silky and expand as your junk does, but maintain their fit. I'd like to get a pair of their microfiber trunks, also.
I've also got a pair of C-IN2 low rise profile briefs, which fit me fairly well..But they don't expand as well.. and they're made for the penis to be worn "down," which is fine with me, but I've got a problem if I get an erection in them...I've got an example of that in my gallery (shameless plug).
It's hard for me to get used to being more constrained, though..Mostly, it's how my balls feel, all bunched up like that. They've enjoyed freedom for so long. I don't know if I'll ever completely get used to briefs again. But, like I said, those CK microfibers do a pretty good job, and are totally different than the tighty whitey fruit of the looms I wore when I was in grade school and junior high.