Without knowing the intended audience it's impossible to guide. Hyperion is rated higher by the traditions of literary achievement, while Ender's Game is more clear and concise, remaining closer to the pew-pew forms of SciFi genera.
Do you prefer Gravity's Rainbow or Inherent Vice?
As for the series in question, I think both were stretched out beyond any reasonable justification for doing so. Ender's Game works more as a stand alone. Do you prefer The Lord of the Rings complete with all the endless tie ins and apocrypha, or a one-and-done story such as Grendel?
