I'd say that pain adds nothing to my experience... some like to spank, or twist a nipple, etc. Also some people are navel or nostril ticklers, which is another zero for me. Certain tools are middling at best, like Wharton wheels, ice, talons, or those things that emit a mild electric shock; a good set of nails is usually more than enough. I am tickled much more by hard tickling, turned on much more by light tickling, but like iloveddub says, not too light so as to be weak. Weak hands make for weak results, as does what I'd call weak contact - namely the sort of random "tapping" of nails or fingers that you'll see in clips from inexperienced lers. Long dragging strokes along the skin - that's the ticket.
(P.S. thanks for sharing the preference iloveddub. 🙂)