I like the 5x10. I'd get 6' tall these brown dogs have spring in their step. I'also like putting the dog house on outside of pen. That way that can't get on it and jump out if that became a problem. Plus that gives them more room.
All of mine are 6 x 10 by 6 feet tall, on cement with a countersunk skike in off corners to keep them from moving (stick it in the proper place in the cement after you first pour it), and all have metal roofs as I've had two that ate their way out the top!! My dog houses now are all dogloos which are dome shaped so the dogs don't climb on them.
