China looks like the obvious beginner Civ to me: Early game bonuses, Science-oriented (and still the only civ in the entire game to be science-oriented), has a quirky tile improvement.
Japan is the obvious beginner civ for fans of the francise imo. With districts and district placement being new, important feature, they're THE best civ to test that mechanic.
England and The Aztecs appear to be better picks for skilled players. A beginner would never, ever go to war early like an Aztec player would and should, while England's bonuses are ALL in the endgame; it would be a harsh learning curve for a newb.