Knit boxers that stretch are my favorite. I found these at Costco last summer. Love 'em! These are very sheer and lightweight. They don't bind like broadcloth boxers. The nature of the fabric makes them a good match for fitted gym shorts and track pants where you don't want excess bulky material. They do nothing to hide your dick outline, which can be good or bad depending on what you are doing.
Before Nautica Boxers, my favorite boxers were FTL. I still wear FTL often.
A few years back, I discovered Kirkland Boxerbriefs that I wore to work. I will also wear the boxerbriefs with some of my gym shorts that are especially revealing when hanging out with family and female friends who don't want to see the outline of my dick.
I still have at least 30 pair of briefs; many different brands. I rarely wear them as underwear. On hot weekend mornings, I will wear just a pair of briefs when I get out of bed. I'll lounge in them while having coffee and doing house chores. Once in a great while, I will wear briefs to work. They feel much different than looser underwear, and I am aware of them all day. When I get home from work, the briefs have to go. Loose and free feels best to me!