Usually it's boxer briefs. I wear jocks for sports, but not the gym. For all the posts on here saying they work out in a jock, I can't say I've noticed many at the gym. I usually see boxer briefs or briefs.
For me, the brand really doesn't matter as long as I've got some support. Not gonna crush my junk to hide my bulge. If it shows, it shows. Seems like most of the women are trying to emphasize their tits or ass anyway, so I don't think anyone cares.