To add to Guess' list, I like the consistency of
Clay Magic, too . . . it's not as stiff as Z-18 (which can be a bit of a pain to knead and form, imo), but it's not so soft as to smear all over the place (ala Meguair's). <goldilocks>This one is juuuuuuust right.</goldilocks>
CM clay also forms to and sticks to your "claying" hand as you use it . . . I liked this, as there seemed to be less chance of dropping the bar. I could remove my hand from the paint and hold it horizontally, and the clay wouldn't fall off. Sticks to your hand, but not the paint, though; it never smeared or left residue.
One more plus, it worked quite well with Meg's Final Inspection (which is both relatively inexpensive and widely available) as lube.
Tort