I have UA cold gear. It's great if you are working, walking, doing activity. If you are sitting it makes me feel colder than I would be without it.
For stand hunting/sitting there is an army surplus store not far from where I work. I buy their thick polypropylene leggings and 1/4 zip top. They keep me warm when sitting but if you have to hike a ways don't layer up until you get to the stand or you will sweat quite a bit thus making you cold when as you sit and start to cool down.
When it gets super cold I just put on my carhart bibs and coat and am fine in really cold temps. My feet will get cols before my body does. What helps most is a poly t-shirt, poly long sleeve shirt, poly vest, then a good insulated coat that cuts wind.