I've kept both corns and ball pythons and they both have there positives and negatives. I prefer a more active (to me more interesting) snake so between those two, I'd pick a corn snake. The positives for corns are tons of reasonably priced color variations that are readily available. Other good snakes for beginners would include, -and can you tell I like rat snakes?- Black rat snakes, Yellow or Everglades rat snakes, Grey rat snakes, Mexican Black Kingsnakes, African House snakes (something a little different), and Children's or Spotted pythons. Ball pythons when feeding are nice snakes- but sometimes will go off feed for months at a time. Which ever you choose, get a captive bred animal. They tend to do better with feeding regularly and you'll have less worries about parasites.