I have fished for bluegill with just about every concievable bait, and I always have my best luck with redworms for sunfish in general. A redworm is what landed that 11.5 inch shellcracker on my avatar.
Whatever is available at the time. Usually tiny pieces of nightcrawlers. they bite on anything, so I say it doesn't really matter. Red worms and crickets are not available here in town, os I naver use them to catch bait. Usually trap them anyway.