My favorite pair of diabetic socks are from EcoSox. I like wearing over the calf socks. Anyway, these socks are non-binding and i believe seamless so nothing to rub against, however they are a bit on the thin side. Here is a link to where I get them.
I also like Aetrex Copper Sole athletic socks for when I play basketball, but they are a bit more on the expensive side. But they are probably one of the most comfortable pairs of socks I have worn. Here is another link
PM me if you have any questions and I will do my best to try to answer them.
I like Balega running socks a lot, light and cushiony at the same time. I've got a few pairs I've probably run 500 or so miles in that are starting to show a little bit of wear but they are still comfortable. http://www.balega.com/
There's another brand I tried at the end of last year called Fit socks that are seamless so they'd be good. They are *extremely* comfy and appear to be very durable. I only have one pair of them. They didn't work as well in the shoes I ran in last summer but I have a new flavor of shoes that they are awesome with! http://fitssock.com/