I too will favor the clay bar. However, I highly suggest
Zaino now that I have had a chance to try their products.
I bought the Ultimate Protection Car Show Kit. The process involved first washing your car in dawn to remove any greese / hard dirt. Then to claybar the entire car (I even did my door jams!

). Then to wash the car again to get off any of the excess residue from the clay baring. Then to polish it with the provided car polish. I did 2 coats of the polish. I was pretty damn tired after all that but my paint looks amazing.