If you want humid, come to Texas & you will know what side to put it on, :main_laugh:LOL!! Here its always hot & humid, never cold & humid. So I'd say the warm side would be best for humid.
I have one one the hot side and one on the cool, figured I'd give them a choice in the matter. In the big tank, two girls hog the warm one and the other girl hogs the cool one.