What are the best underwear for guys?

In terms of comfort, that's a question for each individual man.

In terms of looks:

tighty whities: look best on athletic men who are not too thin or too muscular or overweight. They should fit neither too snugly nor too loosely. Although a lot of people do think tighty whities are sexy, in general a man wearing these is not trying to look sexy. So don't wear these in an attempt to look sexy.

bikini briefs: look best on tall, thin men with lots of muscular definition and a V-shape.

fashion briefs: same as tighty whities, but for men who can get away with fashion-forward underwear. The pouch style front on fashion briefs is generally sexier than a fly front. These are better for a sexy look than tighty whities.

athletic briefs (like jocks with seats): look good really only on athletes, and only when doing something athletic (swimming, running, jogging, etc.).

low rise briefs: the same support as regular briefs...but even more with less underwear.....and hides your underwear waistband very well.

squarecuts/trunks: snug-fitting cousins of the boxer brief but with shorter legs. These look good on any man who is in-shape (tall, short, thin, muscular) so long as they fit well. Also sexier than tighty whities.

boxer briefs: look good on almost all men, including overweight men, and can be sexy, too. They can also help with chaffing issues that are caused when wearing briefs or traditional boxers.

longjohns: modern longjohns have come a long way and look a lot better than they used to. But they are really simply for warmth and should be used only for that purpose.

wicking fabrics: modern fabrics often have wicking properties that keeps sweat (and odor) away from your skin. Look for underwear made of wicking fabrics if you are physically active, sweat a lot, or are prone to B.O.

traditional boxers: these look good on almost all men, including overweight men. But very short men and very thin men should avoid these. In addition, if you are prone to getting erections at inappropriate times, you might want to try boxer briefs instead since traditional boxers won't leave much to the imagination.

freeballing AKA going commando: you like the freedom of boxers but not the ride up and LOVE the way your pants and shorts feel against your naked skin.....best to do in the summer in shorts... though erections are frequent when first trying freeballing.

If you are very hairy (i.e. more than some hest hair and a bit of hair on your stomach), stay away from briefs and go with traditional boxers or boxer briefs.

If you are concerned about making your package look bigger through your clothes, briefs or trunks are the way to go. Men who are well hung might alternatively want to avoid those styles.

Men who don't know how to pick colors should just wear black underwear--it looks good on everyone. Heather gray does, too. White is kind of boring, but it's easy to wash.

Wear what ever kind you want- boxer, brief, boxer-brief, thong, jockstrap or NOTHING. The choice is yous