Top critical review
Good as a compression shirt, not so good otherwise
Reviewed in the United States on March 6, 2020
I've tried S, M, LG, and X-LG in an attempt to make this shirt work for me, without success. It might, however work for you.
I'm a fairly exothermic guy and always prefer these sorts of shirts to baggier t-shirts, buttons downs, pull-overs and the like. I always go for heat gear because unless I am going to be standing around in sub-15F temperatures, anything heavier just makes me too hot.
I also wear these shirts everywhere - to work, to bed, around the house, out hiking, out to restaurants, everywhere, so I can't have anything that is too formfitting. I'm in very good shape, but if feels obnoxious wandering around in something that fits like a second skin. That and it is just uncomfortable for me.
What I wanted was something like I currently have - a lightweight, fitted synthetic shirt that is well-made with no or minimally visible logos. Nothing baggy. Nothing skin-tight. These seemed like a perfect match - UA is a good brand, these have no logos at all, and while they are compression shirts I figured I would just buy up one size.
Turns out this doesn't really work. These shirts are intended to be compression shirts, which means they only really work (move with the body and offload heat) when they are compressing the skin. The material is actually fairly thick before it is stretched out. Buying up a size resulted in a shirt that just ill-fitting, having extra material all over the place and still being too hot, since now the air couldn't circulate properly through the material. That said, this issue aside the material is quite comfortable against the skin and seems to be high quality.
Fit-wise: I am a 5'10" male with an athletic build, ~185 with a <10% BMI. So very fit, but not "swole" in any way. I tried the small, medium, large, and extra large. S was way too tight - getting it off was tougher than getting it on and getting it on wasn't exactly a picnic. M was pretty good, but since I didn't want something form-fitting, I tried L and XL. The L had the general look I wanted, whereas the XL, while still being surprisingly tight, had way too much extra material. However, even the L was too hot during normal day-to-day activities, let alone while running or working outside. The M, L, and XL were all heavier by about 20% than my current shirts (black Reebocks, which I would buy again but the model is discontinued).
So if you want compression and something skin-tight, my recommendation for someone my size is M or, if you have more muscle mass up top, maybe a LG. If you don't want compression, try a different shirt instead.
EDIT: Worth noting that after a few washes, the shirts loosen up considerably. Enough that the XL is now a little baggy around the waist for me (for a compression shirt, anyway). As such, the L is probably the better way to go, once it is broken it, it should fit nicely.