Exofficio Men's Give-N-Go Sport Six-Inch Boxer Brief
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Yeah they're expensive at $23/pair. They're worth it. (Fine to be fair I don't know what your financial situation is, but if you bought any bike specific clothing which you don't technically need then yes they're worth it).

They don't ride up your thigh - at least they don't on me and I have large thighs.
They last practically forever. They're way more cost efficient than previous brands which cost half as much but wore out in a year or two.
They're incredibly good at preventing chafing. I've been walking places that were a short drive to get exercise, the other day 100 feet out I realized I had put on an older pair of underwear that was chafing (wearing jeans), I turned around walked back home switched underwear and the issue went away.

They're just fantastic underwear. Only odd issue is I needed to order a size up for a good fit. And the waist band isn't 100% perfect - ever since I started working out my waist got bigger and it's fine, but I wish it was a little looser (I haven't found any pairs that are better though).

I highly recommend them. Any concerns about cost should be weighed against that they last at least twice as long as most other underwear I've owned.