Under Armour changed the landscape of the base layer world and they continue to stay at the leading edge. I'm a fan of UA for three reasons. 1) the FIT ... snug and soft. It comfortably slides under anything, including fleece!! 2) it's WARM ... which is what it's supposed to be right? ... and it wicks sweat as well as the rest. 3) It doesn't smell too funky after a hard day. I prefer the turtle neck tops as they provide more coverage and go nicely under almost all mid layers which are typically crew necks.