Can't comment about the Artkis as I don't own one, but I do own a buffalo, and it is the bogs dollocks 😊 I've worn one for many years in the army, on the hills and in the woods of Scotland, and under my overalls on various Oil Rigs in the middle of the North Sea in the harshest of conditions for the last 4 winters, and I must say...nothing comes close for warmth and windproof needs.
The shell isn't waterproof as it is pertex, but is extremely quick drying, but hasn't been a major issue for me as it has always been worn under some form of waterproof clothing in wet conditions.
Buffalo recommend that the mountain shirt be worn next to the skin, and while this would undoubtedly provide the best warmth I have always worn a base layer thermal garment under it, purely for hygiene reasons (and also an extra wicking layer).
So I would say the buffalo shirt would be a sound investment. As I said, my current one is 4 years old, and is showing no signs of being ready for the bin yet, so it certainly gets my vote 🖒
Thanks,
Allan