I want to invest in itch proof merino thermal underwear. I understand the function of this base layer is to wick moisture away. My main question is if the thinner it is the better it is at wicking moisture and just use wool sweaters for insulation purposes? I'm asking because I don't know which thickness I should buy. I checked out the 150 at the store but it's very thin. Their original is 260 so should I get this one? Should I get 150, 200 or 260? Which one would wick moisture the best? I want to use this layer only during late fall, winter and early spring.

Thanks
Frankie