There are several extremely good choices, my two favourite brands being Valandre and Western Mountaineering.
My choice these days is a Valandre Bloody Mary which packs light and small, and is good for 90pct of my hunts.
In late season, or when hunting high altitude, I scale up by sleeping on my KUIU Super Down Jacket and Pants, their Ultras or Pros depending 0on how late in the season and how high I am.
If it gets really cold I wear Valandre's Olan down booties, and KUIUs Down Glassing Mitts.
