I was thinking of Milton just before you mentioned him lol.
1) He is one of those throughout the centuries, as a great writer, who cites Shakespeare as a master. When the other "players" continue to call you great, you're great.
2) Sam Johnson, one of those great writers who lauds Shakespeare extravagantly, also said of Milton (rough paraphrase) "Everyone acknowledges the greatness of Paradise Lost. No one wants it to be longer."
Its futile to discuss which writers are original and which aren't. All writers are influenced in style and theme by writers who went before them. Themes like Dr. Faustus have been taken up several times in original ways. There are many writers who I believe are Shakespeare's equals, but Paradise Lost and Paradise Regained are truly impressive. Good luck getting your students to read Milton.