I have worn an Icebreaker zip-neck tee for a couple of years with great satisfaction -- I much prefer it to the Smartwool it replaced. The Icebreakers (I have two) were VERY scratchy when received and required several washings to de-scratchify them -- and this from a guy who has for over twenty years touted wool as the true "miracle" fabric. I also wonder how much several washings affects the life-span of the shirts. These are wonderful and, for me, nearly four-season shirts. However, when very wet they stay very wet, which I re-learned this summer on a five-day trip.
I just succumbed to a sale and ordered an Acr'teryx Accelero Comp Shirt from Backcountry.com for 30% off -- and it's still expensive. However, I thought I'd give it a try to see how it does especially in damp weather. With all the apparent choices, it is still not easy, especially living in very rural Maine with LL Bean's two hours away and better stores much farther away than that (think four hours to the Boston area); I rarely get to see things before buying them.