Under the Nio Amphi
I like a longer compression brief under my touring shorts. They must be light, breathable, and seamless. Cotton just not work for me, it holds too much moisture, gets heavy, and rubs. Polypropylene is what I look for with a little spandex.
I am still fine tuning sources but for now my top sites are His Room, they have several brands available, and Champion. I am not sure about Champion yet; their quality seems to have decreased dramatically. The construction on their stuff is still fine but their Double Dry material is a big drop off from the poly they used when they were Duofold.