Suggesting a racer as a second plane is worse than suggesting a Yak. Any of the planes from the list above will work as a second plane. Me personally, I would suggest a stick as others have or a Sig 4 star or Goldberg Tiger 2, but the OP isn't interested in those. What makes for a good second plane is good slow speed stability combined with moderately neutral handling and agile maneuverability. Any of the planes on the above list will work, as will any of the traditional tried and true second planes that get suggested over and over on the forum. A racer does not meet the requirements, as they land hot and can get into high speed stalls that a beginning pilot won't know how to recover from.