Howies Natural Base Layers have won loads of awards and loyal fans, and work really well as normal riding shirts.
The Short Sleeve is a close-fitting T-shirt made from a very fine, stretchy merino wool fabric. Incredibly soft and comfortable, it wicks reasonably fast too. Wool dries slower than synthetics, but it’s warmer wet than dry so you won’t get chilly or clammy. It’s naturally anti-bacterial too, so it takes a few rides to make the shirt stink (ideal for multi-day adventures). It doesn’t itch at all either, although it can showcase your nipples dramatically.
The price is steep for a T-shirt, but it’s a fantastic base or outer layer, and it’s impressively durable. Long-sleeve and zip-neck versions are available too.