Finding men's underwear most comfortable for your specific shape and size is more personalised than most product guides acknowledge. Body type affects which cut works best. Taller blokes often find boxer briefs sit better than trunks. Broader builds may find briefs more comfortable than longer cuts. Men carrying more weight around the middle often benefit from a higher-rise waistband. These aren't absolute rules but they're useful starting points. The men's underwear most comfortable for your body is the one that fits your actual measurements and shape, not just the generic size label.
What I think helps most blokes shortcut the trial-and-error process of finding men's underwear most comfortable for their shape is starting with quality and narrowing from there. Cheap gear is never going to give you a reliable signal about whether a cut works for you because the poor construction interferes with the fit assessment. Start with quality options, try 2 or 3 different cuts, and you'll identify your preference within a month.
A bloke I know had never found underwear that felt properly comfortable and assumed it was just the nature of the product. He was a taller bloke who'd been wearing trunks for years on the assumption that they were the right cut. He tried Barramundies boxer briefs on my recommendation and said it was the most comfortable underwear he'd worn in his adult life. The cut matched his proportions better. Same quality brand, different cut, dramatically better outcome.
From my experience, finding men's underwear most comfortable for your shape is a 1-time investment of attention that pays off for years. Try quality options in a couple of different cuts. Your body will tell you quickly which one works. Barramundies makes quality across their full range of cuts, which means you can run that test without compromising on the quality variable. Once you've found the right combination, stock up and stop thinking about it.