layers are your best way of staying warm, and start with a good first layer that wick's away any moisture/sweat!
the biggest key IMO to staying warm in cold temps when sitting still, is being DRY before you STOP moving!
as moisture sweat
is the enemy, after your core drops from any activity that makes it, it then causes your body to work harder to stay warm and your body's battery dies faster on staying warm LOL
so getting to your stand without braking a sweat and wearing as little as needed is one way to help you stay warm
THAT or wear in some gear and REMOVE and replace with fresh DRY gear once on stand!
before actually suggesting any specific type or brand,
if you Kiev us some more info odds are you will bet better answers
like when your trying to stray warm hunting, will you be sitting in a tree stand, a ground blind, on the ground
as the type of actual hunting your going to be doing matters on what gear works better!