I have guide pants and jacket and they both fit athletic/true to size. I have their entry level pants also(cant remember the name) I'm 5'11 170 and I have a medium. Very good quality gear for the price. Guide pants are the most comfortable pair of pants I own.
I had the guide pants, jacket and vest, peloton hoodie. I'm 5'11 185 and wore a large in all of it. The stuff fit great and is really nice gear. Was caught in a pretty good snow storm first rifle season last year in Colorado and stayed dry and warm no problem.
I have Yukon jackets and a pair of pants. I wear an XL with only fleece shirts or something like that underneath. I bought an XXL to layer over a puffy jacket and a heavy fleece shirt.
I have a large amount Kuiu. Some of most lines and layers. It the only thing I wear on the mountain. It is athletic cut but I think pretty true to size. The super down line is great. I have the Chugach rain gear and it's a great outer layer. I have found that I like it some much on the mountain that I have started getting pieces to wear everyday that aren't camo. A friend uses the Teton line and likes it as well. I see other lines out there and for money and value I won't change.
+10 on the yukon rain jacket. Bombproof sleeve gussets perfect for real rain/snow/outer layer. Have many items from them as well but I went a size up 6' 185 just don't like tight sleeves. Also, love the zip off wool long johns. Guide pants in my photo, wasn't crazy about the mesh pockets on a cold season pant so I sewed some cloth inside. I got a puffy labor day sale from Cabela's $69 works wicked good