As far as briefs, Saxx and ex officio are good. I've beat the hell out of those doing work, and they've been bulletproof so far. I was surprised to see all of my KUIU, BlackOvis, and Sitka merino form holes pretty quickly, and that was just daily wear—nothing really stressful.
I picked up some Eberlestock Lochsa stuff on sale a few months ago, and it's impressing me. I'm sure it will be more durable than the KUIU and Sitka. It's not cheap but it's very good baselayers imo.