I have good experiences with the "Heattech" line from Uniqlo. It's some synthetic formulation of fibers but does it's job quite well for me, at low cost.
Funny that, I'm wearing the Heattech Ultra turtleneck right now, it cost 30€ and is probably the comfiest top I own. The reason I was asking for alternatives is simply that I can't get a non-turtleneck one in my size because they sell out immediately.
Overall I'm really happy with all the clothes I got from Uniqlo.
Overall I'm really happy with all the clothes I got from Uniqlo.