I would advice not have pulling all keycaps off a keyboard be part of the competition, because with higher speed comes higher force and you could potentially damage keyboard switches and keycaps. (especially with Alps)
I think it would be fun to have a compo for populating a keyboard with keycaps though. Let's start with each contestant getting the keyboard's keycaps in a bag, unsorted and the winner would be the first person to have populated a full-size keyboard correctly.
This part should however allow the contestant to pull the odd keycaps that have been placed wrong.
BTW, I think the fastest keycap puller is the H-shaped one. More stable than a ring-type, and therefore faster. No need to wiggle.