I was doing a go-back-&-reread-more-obscure-Shakespeare thing not so long ago, and I was surprised at how much I enjoyed King John (http://www.shakespeare-literature.com/King_John/).

Diverting slightly from Shakespeare, two of the plays in my M.A. thesis were Peele's Edward Longshanks and Marlowe's Edward II. Definitely a contrast between two radically different monarchs.