Best merino wool shirt.

[Stixbowdrew]

Smart wool, icebreaker. No need to buy "hunting" merino

[cacciatore]

I use Armani Cachemire wool a Little expensive but cozy and light weight. Lol

[m laughlin]

might take a look at Schnee's rifleman's shirt.

[PistolPete]

I like Redington the best right now, and it's fairly cheap. Whatever you do, look for blends with 80:20 wool:nylon, since it'll be stronger and more durable. And protect it from moths! After washing and drying, store your merino in a ziploc bag and freeze it for a day (to kill any larvae) before you put it back on your shelf.