I'm going with the cotton ones...
I gave all three a couple sessions on the ice. All were better than my original cotton socks, simply because the ankle of the thicker socks is ribbed, whereas I was careful that none of the thinner ones are.
I actually did not mind the nylon socks in the skates - my custom Klingbeils held my feet in place well and it did not feel slippery. They were also the thinnest. I thought sweat would surely be a problem since they were so thin, but it wasn't. Yes, I got sweaty in the same places, but no, my ankles didn't end up hurting. The nylon socks were actually my second favorite, though they were atrocious to use in regular shoes or just walking around the house as then the slipperiness was NOT FUN!
My least favorite were the rayon/acrylic/nylon blend. They weren't bad but just weren't as good as either the nylon or primarily cotton socks. They would work fine in a pinch and were better than the thick cotton socks I was wearing before.
Ultimately, I'm going to keep skating with the nice primarily-cotton socks (
http://www.maggiesorganics.com/organic-cotton-knee-high-sock-tri-pak-3-pair/). I am glad these lived up to my hopes for them being the best. They have the best sweat absorbency while still being thin, and also my feet got the least cold using these. They are "just right" and I like that they are mostly natural cotton and organic at that. Skating makes one care about their feet entirely too much.
![Wink ;)](http://skatingforums.com/Smileys/default/wink.gif)
As for the sweat, I've noticed that regardless of sock type, I get sweaty along the top of my foot and front of my ankle. When I take my skates off, this part of the sock is always visibly damp. However the other parts of the foot have obviously been sweating too, because the leather inside my boot is wet on the sides and back also. The tongue is rubber on the inside, and I think this repels more moisture to build up in that part of the sock, whereas the leather on the sides and back absorbs some of the moisture so the sock looks more dry even though it was sweaty too. In the thinner socks I notice sweat after a much shorter time skating, but it isn't a problem. With the thicker socks, it becomes a problem after there is enough sweat to saturate the thicker socks.
Perhaps whenever I get replacement boots, I can get them to line the inside of the tongue with leather? Dunno if that makes sense or not...