another one for wool without a doubt. I elk hunted in Under Armour two years ago for 12 straight days, my brother and my dad told me that I stunk like an outhouse, I haven't bothered with it since, plus I did not like how it felt against my skin either. I find that wool stays "stink" free better than any other fabric I have tried.
As far as brands of wool take a look at Justin Charles, Ibex, Smartwool, KUIU, Firstlite or even Filson. If wool makes your skin itch I would not recommend the Filson, if you are looking for a soft itch free next to skin wool then I would try the Justin Charles, Firstlite, KUIU or Smartwool. As far as insulation goes I always start with a "base layer", most of the above companies make a base layer and will tell you this is the layer that you should wear next to your skin, this is typically the thinnest layer that they offer which helps wicking moisture away while staying dry. After that comes the more "thick" layers. For early season elk I typically wear a base layer over a camo shirt. I typically do not need another insulating layer of wool until later in the year when the temps start to drop.
The only down side of wool is that it is not wind protecting, and if not properly cared for will typically have a short life.
The fact of the matter is that mountaineers are still wearing wool on Everst, this should account for something.