The best unisex panties I have found so far are Jockey "No Panty Line Promise" Tactel nylon bikini panties. You can find them at Jockey factory outlets, Kohls, JC Penneys and other department stores. The fit is absolutely perfect, like they were made for us!
Almost any department store because they make female undies look like the jock shorts, including Victoria secret and others....the best to you