There are a ton of Arthur legends out there, since people like making up tales about them. It's like an early version of the Marvel comics universe, where there are tons of people doing interconnecting things. It's almost impossible to read them all.

My favorite adaptation, though, is probably The Mists of Avalon, though I have a soft spot for The Crystal Cave.

Knights, magic, latent homoerotic subtext.... What's not interesting? ;)