I am glad I created my own layering system.
The warmest thing right now is high loft goose down (by weight and packability)
Yes, putting it under another garment does compress it and hurt the insulation, but this is also true of any "puffy" style insulation and even when compressed slightly, high loft goose down is still the standard.
I would buy 4 items:
1. stuff sack to carry this stuff in
2. high loft goose down thin puffy vest (750 fill power or more....with bonus points for the down being coated with a water repellent)
3. high loft goose down thin puffy jacket
4. a thin, wind-repelling layer (wind shirt)
Pack the sack with wind shirt in bottom then jacket then vest (in order of putting it on)
Walk to the tree an outer layer and base layer (I walk in slightly cold so I don't sweat).
Once at height, I put these on my base layer
And then the vest, then jacket, then wind shirt, then exterior jacket.
The thickest jacket I usually wear in WV is a medium weight one (fleece one from Midwayusa that isn't fuzzy on the outside but has substance).
I have low body fat and am somewhat tall and get cold easy. I am never cold in this layering system that evolved over several years.
Links in case it helps:
here's a good jacket i wear....they go on massive sale in the spring...sorry it's bad timing
I also have the same thing but a vest, I do not see any down vests there now at Eddie's
Then this goes over the down but under the jacket
Buy Charles River Apparel mens Legend Windshirt (Regular & Big-tall Sizes) and other Windbreakers at Amazon.com. Our wide selection is elegible for free shipping and free returns.
www.amazon.com
I never walk in with a windproof sweat box on me unless it is raining and I have to wear a waterproof jacket.
This is like a Tyvek vapor barrier over your down and turbo charges it.
With these things and something like this jacket over it all (and just a medium base layer)
The workhorse of the hunting lineup, the MidwayUSA Prairie Creek Softshell Jacket will soon become your favorite. This extremely comfortable, windproof...
www.midwayusa.com
I can easily sit all long in freezing temperatures.
All this stuffs down to the size of a football in my pack and only weighs a pound or two.