For next-to-skin I like cashmere the best of all woolens. Merino is second best among those I've tried. Both are light and warm and SOFT. Keep a sharp eye out at the thrift stores in upscale neighborhoods, and you'll find cashmere and merino sweaters for $3 or $4. Brand-new sweaters might cost a hundred times more than that.
I also have no problem with the synthetic T-shirts as a winter base layer. I just wear my summer Ts, especially the ones that are starting to look a little frayed or faded.