It's a tussle between underclothing that gives you freedom and room (boxers?) and underwear that supports the weight (briefs?). I suppose boxerbriefs could be expected to do both, but the ones I have tried fail on both counts.
It's hardly surpising that we find either less than ideal, given that even with my dim mathematical brain it is clear to me that I and plenty of other lpsg members have 4, 5, 6 or more times the "normal" volume and therefore weight to deal with. Oversized balls make it even more of a problem, if you have them.
I know a lot of guys avoid jocks, but at least, if like me you get them custom made to fit you - they handle both weight and volume. No groin strain, no squashing, no friction sores, etc. Once you get used to the feeling, it is fine.