I got some wool socks last year because someone told me they were superior for wicking away moisture and staying warm in winter and cool in summer. Up until that point I had always gotten by with cotton socks without any problems (no blisters, etc.). I also bought waterproof low-top Merrell hiking shoes.
Here's what I have found:
I can't really do the waterproof shoes with anything. My feet sweat too much without the ventilation, but they are definitely worse with wool versus cotton in the summer. I thought Gore-Tex was supposed to be the answer to that, but others I have read said those still don't really breathe, else they would allow water through.
So I have Merrell Moab Ventilators that I really like. I can do 18 miles at 80-90 degrees in cotton socks with those and not get a single blister. However, if I wear wool, at around mile 7 I find that my feet start to exhibit signs of immersion foot. I can feel blisters already starting to form. I've somewhat mitigated this with polypro liners, but still not as good as cotton.
My problem is when I am in warm weather with the possibility of several water crossings and hiking all day, like on Whitney in the summer. Anyone else out there have the same problem as I do? I wore cotton socks my first year on Whitney with some non-WP Columbias, and the rain and big wet snow we encountered had soaked my feet, but I didn't even notice, and it wasn't until towards the end when I dunked my foot on wet water crossings that I even felt my foot was wet, until I took off both shoes and saw both socks were completely soaked, and I had no blisters! Not sure what it is about cotton that makes it so I don't get them.