If you are looking for the very best I would suggest Ferodo DS3000 pads but have no clue where you would get them in the USA. They are used in NASCAR, Indy and a bunch of other pro races.
www.ferodo.co.uk
They are true race only pads, have just about the best friction performance you can get and have a thermal barrier layer that reduces significantly the heat transfer from the pad/rotor to the caliper/fluid.
I had a set made for me (nil stock of Vette sizes) and they cost around USD$400.
If you want cheap, you'll need something else but buyer beware (you get what you pay for). If you want to do serious racing please don't by the cheapest. Try and pick something mid range. I'd hate to see you wreck because you saved $100 on cheap pads.