Let me cast my vote for the exofficios - they are easy to wash and dry very quickly; perfect for the Camino. I've used a pair of their boxers for years when traveling.
I normally would never wear jocky or brief type underwear, but, in a fit of uncontrolled pack weight obsession last year, I took my scale to REI and found exofficio briefs weigh a few grams less than boxers, so I bought a couple. (They still let me into the store, but they do look at me funny.) That's one weight saving I regretted; my one pair of boxers was more comfortable than the briefs, although the briefs were tolerable.
Karl