I recently had the chance to use a vintage Griswold cast iron pan to sear some steaks at a friend´s place and I loved it.
My advice is to find a Griswold in reasonable condition, no cracks, flat and little or no rust, if it is severely caked with grime all the better then the surface is likely well protected. Strip it with oven cleaner and remove all traces of carbon buildup until you have only the bare metal. do a final wash with very hot water and soap and quickly dry with a paper towel. Then begin the seasoning process.
I use flax seed oil which I apply liberally and then remove as much as I can with paper towels. Then bake it for an hour and a half at about 110degC, let it cool and repeat the process. Then repeat the process two or three times at 220degC After that fry bacon a few times then do some eggs and you will find a friend for life.
I also have some carbon steel pans which when using over an induction burner are incredibly responsive, like a sports car on the stove. I want to get my hands on a De Buyer sometime soon.
For general browning when I want to make a pan sauce, I use an All Clad, no worry about stripping the pan´s seasoning when deglazing and it offers a lot of control over any heat source but it is not as responsive as the carbon steel pan. This is the pan I would recommend based on what you are currently doing with a non stick.