I do not use the "base layer" concept in my layering. I have a hiking under shirt (cheap very light weight loose work-out shirts of various blends of cotton and nylon- Danskin at Walmart for about $10)that I simply take off and wash at the end of the day, and then I put on my sitting around clothes- I have one light wool layer and one 100-wt fleece. Over the undershirt I wear a long sleeved loose brushed nylon fishing shirt. The undershirt gets most the stink and is washed daily. In the Sierra, weather is good, so I actually wash both undershirt and fishing shirt most days.
As for my sitting around, sometimes I prefer the wool, sometimes the fleece. My "base layer" therefor is NOT part of my hiking clothes. IF it were so cold that I would hike in an insulating layer, I would use the wool, because it breathes better, in my opinion. I have Ibex wool. I have never used any high-tech expensive synthetic base layer. I really dislike tight layers or really stretchy stuff.
My husband is a real "stinker", so if he wants to sleep in the tent with me, he has to wear wool! He actually also hikes in a cotton T-shirt and does not wear it at night.
Most of our stuff is pretty old. I think some of the newer synthetics stink a lot less.