Replacement: Marmot Lightweight Crew T-Shirt (Cocona)

Arcteryx Motus is very good!

Just about every running/fitness/hiking/athletic brand makes lightweight tech t-shirts: Nike, addidas, UA, Marmot, Patagonia, Brooks, New Balance, and on and on and on. In the US, the cheapest place to find them is Marshalls or TJMaxx. They always have several options in the $15 to $20 range. I've got three long sleeve Marmot Power Dry shirts that I got there for $16 each.

They all make very thin warm weather base layer options, often with breathable mesh. The Patagonia Capilene 1 shirts are paper thin.

If you want Marmot, any of these short sleeve shirts would be fine:

http://marmot.com/products/men/shirts–pullovers/training

The main thing to look for is fit. Some are looser fitting. Some are tight and stretchy.

I'm in Europe, so prefer to not order from the .us
I read a bit more, the prolitegear baselayer comparison is very helpful.
I also noticed that my current T-Shirts above are rather on the heavier side.

I'm considering these:

Rab Aeon Tee
http://rab.uk.com/products/mens-clothing/tees/aeon/aeon-tee.html

Patagonia Cap 2
http://www.patagonia.com/us/product/mens-capilene-2-baselayer-lightweight-t-shirt?p=44915-0

Arcteryx Motus Crew
http://arcteryx.com/product.aspx?language=EN&gender=Mens&model=Motus-Crew-SS
Although I didn't find information about the wicking etc of this shirt.

The patagonia and rab have quite good results:
http://www.prolitegear.com/site/best-baselayer-reviews.html

I've now received two Rab Aeon Tees – very lightweight and thin material. I was surprised that the mesh is quite fine/dense (not sure what the right wording in english is).

My previous shirts have a much wider mesh.. I'm curious how this affects breathability, if I can tell the difference. Also unsure what role exactly the surface area plays, which is smaller I guess with such thin shirts.

I think I will also try the Arcteryx, Patagonia Cap 2 and Marmot ThermalClime

Did some more testing.. the Aeon feels quite nice, and although it has this dense structure, it dries as fast as the Marmot tees I have.

I just saw that Arc'teryx has quite a lot of shirts with various polyester weavings

The Patagonia Cap 2 (Polartec PowerDry) is a great winter baselayer. Too hot for summer sweaty conditions, IMO.