I have purchased five or six pairs of these Fruit of the Loom thermal long underwear for my boyfriend over the past several years. He's a contractor and works outside even when it's freezing cold out. I don't know how he does it, honestly. I'm a baby about the cold. He seems to like them, and hasn't complained that they a) don't keep him warm enough, or b) make him sweat his butt off. So I guess the midweight is the way to go.The thermals are well made, he wears them pretty much every day in the winter, so they get washed very frequently and have held up just fine. No fraying or wear holes from the numerous washings. He's super hard on clothing, all of his work clothes get destroyed, but these have been ok. I guess they aren't subject to as much abuse as his jeans are, but the knees and backside are still intact and the cuffs have not started unravelling.The sizing and thickness are just right- not bulky underneath his jeans, but roomy enough that he is comfortable moving around, bending, squatting, etc. I get him Mediums and he wears a 31x32 pants and has pretty large and muscular thighs so they're a bit more snug around his thighs, but material is kind of stretchy so it's not too tight. The legs are long enough to reach his ankles, and the rise is high enough that he doesn't flash a plumber crack when he bends over. The cuffs are thin and flat enough that they don't feel weird with work boots. These thermals are comfortable (and modest) enough that sometimes he'll get home from work, take off his work jeans and just lounge around in these, without looking like he's wearing a pair of my leggings, lol. I don't know if the white ones would be as modest, but the black and gray ones are fine.One can never have too many thermals when working out in the cold, so I'll continue to buy them for his lame-but-useful stocking stuffers.If you have any questions or comments, feel free to let me know below :)