I went with hawk ceramic pad up front and have some discount semi ceramic in the back. I am not sure what the difference is in the two but someone will chime in about the differences.
Better braking, less brake dust on the wheels, less wear on the rotors. I've had ceramic front and back for over a year and they have little wear. I'd spend the extra again.
i have the hawk hps with some powerslot rotors, and although they stop really well, i find that i get a good amount of brake squeak. which i do not care for.
The general rule is HPS for drag racing, and Ceramic for road course type racing.
If you are in a built auto for drag racing, you won't be able to take advantage of the ceramic pads as they require to be heated up...assuming you are running line locks. With the HPS, you don't need to heat them up. The HPS pads don't require to be heated up.
For drag racing, the stock brake lines are more than fine, they wont flex enough to require SS. For road course, the SS lines are quite helpful.