I just started trying to perfect what works best for me. I get hot when I'm going hard, but cold when riding the lifts.
Right now I'm playing around with a Columbia omni-heat base layer. It's a tight under armor style shirt with that silver reflective shit on the inside.... whatever... it was all half price so worth a try. Verdict is still out on that.
From there I've tried just a fleece, and just a Columbia omni-wind half zip shirt. Both left me a bit too cold when the wind blew. But, combining the two left me wet with a lot sweat. So much sweat I thought my coat might not be blocking the water so I took a shower in it today. It's good to go. I was sweating so much I went through a thin base, a NF fleece, and a med. weight top layer.
I think a lot of it is going to depend on how you feel comfortable when out on the mountain. I like to be on the warm side, but not so warm I'm drenched in sweat.
Start with whatever base/shell you like and layer from there until you find the sweet spot.