I have four pieces of Sitka. One is a base layer (next to skin). I think it is called a Core Midweight Zip T. I have the Duck Oven mid-layer jacket. I love this thing. I wear it all the time around my property, on it's own. For waterproof Gore-Tex outer jackets I have the Delta Wading Jacket and the Hudson jacket. I wore the Delta last weekend with the Duck Oven under it in 25 degree temps. Could go colder and be ok, depending on layering. Sitka is owned by WR Gore, so they use the highest grade of Gore-Tex in their jackets. There is not a breathable waterproof hunting garment on the market that is any better than Sitka. I like a previous poster's comment of "buy once cry once". Sitka is expensive but a long term investment. I am in my 60s and I do not envision ever buying another hunting jacket.
In the past I have owned Drake (junk, at least at that time), Columbia and Cabelas. I really like the Columbia jackets but they will not keep you dry like a Sitka.