On your topic ... I like fleece. Thin to thick, it seems to be the best for me. The First Gear fleece liner I have is on the thick side, but not too back. Has the zip up neck and under that I usually where at the most a long sleeve shirt. High 30s and I am still fine, forearms can feel cold on long rides, but not uncomfortable. I usually carry a thin sweatshirt that would fit under the fleece liner easily just in case. Legs are usually thermally lined over pants, fleece lined jeans and if really cold a pair of thermals under all that ... I have a few different thermals, not really a need to search out others since so far, I have no issues. My FEET are my big issue ... I think that may be the only place I want to think about heated gear (my grips are already heated.
The real issue I have is stopping for a few minutes - you can heat up in a hurry in all that Mr Bebendum gear.