I've been shopping around to try to find a decent WYOB body briefer.  I wear a 36G bra, so ones with the bra built in are pretty much not an option, and because my chest is large, it often makes the straps on the WYOB shapewear dig into my underarms something fierce.  The design of this briefer is so much better in that area than any other shapewear I've tried, by far.  The straps are also nice and wide, and padded, so they're pretty comfortable.

So far as the sizing goes, I'm 5'9" and currently 200lbs with an approximately 37" waist, and the large fits fine, even though I should be at least an XL, even XXL, according to their size chart.  I could go for a little more length in the torso and a little less stretch horizontally, but I know I have an unusual body type and don't expect to ever find something perfect.

Ultimately, I'm generally a really stingy person, and I've bought more than one of these to wear all the time.  It's definitely worth it.