Under Armour Coldgear tops (& leggings).
Very soft, comfortable, and warm.
You can get them in compression or fitted, depending on your preference.
I use them as my base layer (top and bottom) and love them. Switched from regular wool and polyester base layers.
I agree. They are warm but more importantly for me is they can deal with the sweat output. I have lived in Minnesota my whole life and could never deal with sweating during the winter. There was just no way to stay warm with as much as I sweat. Some how Under Armour Coldgear controls my sweat and still keeps me warm. I even wear it when it is not that cold. I just sweat right through anything else. It is very warm also.
I could see that some people would not like the tight fit for snowboarding but if you want to control your sweating and stay warm you can't beat UA.
Every man is born an original, but sadly, most men die copies. -Abraham Lincoln-