I'm a synthetic guy. My issued stuff hasn't failed me in the worst of cold climates and conditions. Works great for hunting. Only had to buy quality outter layers. My system is:
- Silk weight base layer top and bottom.
- polartech power dry grid fleece top and bottom as second layer
- northface Verto as third layer that acts as a wind break/vapor barrier (better than windshirt imo)
- $20 black Columbia fleece over that if it's really cold. (Way better than issued green fleece)
- I use goretex soft shell bib and jacket as the outter layer.
- wool hat and glove liners (retains some r value when wet vs fleece hats/gloves)
I had Velcro sewn down the legs on the grid fleece so you can just drop trow and put them on without having to take boots off Ect.
If it's late season/ muzzleloader I usually wear the first two layers and then use my cabelas Berber fleece top and bottom. That's only for the coldest days though. That stuff is no joke warm.