I'm a sucker for the swiftwick 4" wool socks for winter. They seem warmer than most of the other wool socks I have. I buy the seconds (I like 2" height for summer) at Performance sales for $5. Can't go wrong. I've also stopped buying mostly white socks because they are harder to keep really white.

Any reasonable "moisture wicking" material would be better than cotton socks. I prefer them sized a bit large rather than a bit small to avoid holes.