I used to just wear a cotton T-shirt. Then I move to Tec t's from Nike, Sugoi and the like. No longer will I wear a synthetic next to my skin.
www.icebreaker.ca 100% Merino wool. Cool in summer, warm in winter. Breathable, fast drying and does not "stink". The store is on West 4th at Arbutus. Yes, it's pricy but it works well. I have their shorts, sox and several long sleeve T's. If you ski, board, sled, etc it's perfect. I tried bicycle shorts but they don't work for me. Check it out. Cheers