I realize now that I haven't seen many film adaptations of the Arthurian legend. I've seen Disney's Sword in the Stone, although I don't remember that much about it. I saw First Knight in the 90's, with Sean Connery and Richard Gere, which wasn't that good... and I saw the TV miniseries Merlin, starring Sam Neill. That one was pretty cool.
I shall take recommendations from this question.