I think Missileman's suggestion of the new Super Cub is a good one, I'd like it a lot more though if it were a 4 channel.

http://www.hobbyzoneairplanes.com/ho..._super_cub.htm

Hobby Lobby is big into electrics, & they have a number of electric ARFs & RTFs to choose from. They also have full build kits as well.

http://www.hobby-lobby.com/

For an electric beginner plane this one is my favorite in the parkflyer category. The reason for that is it is a true 4 channel plane with a rudder & elevator, not a V-tail. I think this plane teaches a beginner far more than any of the Aerobird series planes can. It flies & controls like a real RC plane. Ailerons, rudder, elevator & throttle.
I think some time on a plane like this will get you ready for more advanced planes much better than the Challenger. It comes in both RTF or ARF versions.
The ARF version includes everythig but the radio & reciever. Here it is.

http://www.parkflyers.com/html/begin-air.html