I have 3 types of cold weather baser layers. They're primarily for skiing but I've successfully repurposed them for cycling.

Icebreaker Long sleeve merino
I have 3 of these in 200 weight, one 260 weight (gonna get another soon). As one poster said, this is the magic material. It breathes a bit too well so one needs some wind block.

Under Armor Cold Gear compression mock turtleneck.
Plastic base layers block wind a bit better.

Nike Combat Pro mock turtleneck.
I prefer this to the UA - only slightly though.

Windy days I lean to the plastic (UA or Nike) else I prefer the Icebreaker merino. I'm an Icebreaker fan boy - have a pair of Smartwool long johns and they're fine but not as good as the Icebreaker underwear. If it's close to freezing, I use a Nike or UA ls summer base layer under my Icebreaker 320 weight hoodie (mid layer) and my jacket/gabba goes over that rig.