Solid running socks. I can't tolerate socks that are too thick with the shoes size/type I run in. I will get black toenails after a long run in socks that are just a bit too thick. I run in a permanently warm environment, so thick socks aren't really needed for warmth either.Thorlo socks have proven to be perfect for me. Great Achilles rub protection, perfect amount of heel, forefoot and toe cushion and comfortable, effective compression over top of foot and arch.I still get blisters on just one foot and in one area, but I think it is more an issue with the running shoe I use. I remedy it by putting KT or similar athletic tape over the area for my long runs and that dramatically reduces size of blister (if I get one).I've used 2 pairs for about 800 miles running this past year and they are holding up just fine. No holes or thin spots. Very mildly stretched, but given the miles in them I'd expect that. Recently picked up 2 more pairs and they felt a little tighter on my foot. Love these socks.