As a Team Leader for a trail crew in SE AK I lived in a tent for 9 months. While double kneed carhartts shredded, rain jackets failed, and I lost track of how many tents I went through, the one thing I could count on day-in and day-out was a comfortable pair of quick drying exofficio boxer briefs. They retained their stretch and never chaffed even after wearing one pair for a week straight of rain and running around trails.
For the entire 9 months I was in Alaska I had no other underwear and each pair is still going strong. Not once did I find these uncomfortable. If I had the cash I would get rid of my cotton and replace them with these. Just go with it, these are fantastic!
I am 5' 7" and 150 lbs with an athletic build and a small was the perfect size for me.