These undies are very soft and breathable, extremely comfortable, and most importantly- hold everything in place. The only issue is that they can ride up a little bit, but I have a very active job, so your mileage may vary.
I bought these after having stage 1 phalloplasty after another guy recommended them. Super comfortable waistband, fit true to size, keep my bits nice and in front and not squished between my legs. Don't see them lasting for years due to the softness of the material, but at $33 for 4 pairs, they're worth the money.