I cook all the time but I'm still young and so far have not been terribly discerning about what cookware I use except the only things that have stuck around in my kitchen are items that I have not destroyed.
I have an all clad sauté pan, a couple of nonstick pans that I keep around for nonstick pan jobs, a couple of different sizes of antique cast iron skillets, an antique cast iron griddle, a couple enamel coated dutch ovens, various sizes and finishes of pots and pans. I don't find myself needing any other pots and pans, but I certainly enjoy acquiring them, and carbon steel doesn't seem as though it will break the bank.
What is it best for? What type of pan do I buy? Season like cast iron? I usually do a quick layer with leaf lard in the oven and then just be careful about what goes into it til a good layer builds up.