I've got several different base layers ranging from Spyder to C9 (cheap Champion stuff from Target), as far as I am concerned they all work pretty much the same. I also wear a Spyder wind-stopper jacket underneath the insulated ski jacket, which has so far kept me warm pretty much in any kind of weather.
I've been wearing Smartwool silk a my next-to skin layer and Orage Distant pants and jacket for my fleece layer. That, combined with a shell, seems to be a nice and light, yet very warm and effective system.
Last season i wore a Burton AK 3L jacket with patagucci capiline or one mountain lightweight base layer or smartwool next to skin. Those all worker really well and the one mountain base layer has a dope graphic.