Modal or bamboo underwear - soft, stretchy, silky, the solution to everything I hated about cotton underwear. They are usually more expensive than Walmart (or other box store) brands and take more care when washing, but to me are definitely worth it. You can find them for fairly good prices on Amazon if you don’t want to splurge on name brands, but you have to do the research and check the reviews. You can get them in boxers, briefs, and thongs for men and even more styles for women.