Regarding socks, what Aggie00 says is true, plus personal preference. Mostly, you want socks, like shoes, to fit your feet. If they are too short, then sometimes the shoe fabric in the back can rub. If they are loose, then they can bunch up and rub in weird places. Any small thing that you might not think much about mushrooms into a big thing that is all you can think about on a long run. Especially if that something is a big ole blister.
For most daily runs, (<10-12 miles) I wear whatever. Just a well-fitting cotton blend sock. I have a few others tucked away in the drawer like these:
Socks that are more expensive like Thorlos and Bombas that I really like for several reasons:
I am old and losing the 'fat' on my feet, so they help keep my feet from feeling so tired on longer runs. (longer is relative). They also keep my shoes from slipping (skinny feet) so I get better pushoff on my stride. The Bombas I received as a gift but I probably wouldn't usually buy them for myself. They are nice, though. The Thorlos I have had for awhile, I am not particularly hard on socks.
I don't like those styles so much when it is hot so I also have thinner socks that are still absorbent to keep my feet from squelching (I have decided that is a technical term exclusive to Texas running ) in the summer.
I don't wear racing flats anymore, but I liked the Asics socks for that.
My suggestion is usually to start with the cheaper blended socks and see how those work.
I am so happy to be running again, I guess my feet are happy, too!