If you've some experience with the J3 I'd look at the Multiplex MiniMag, it's as durable if not more so than the Super Cub, can be set up as 3 channel to start with but you install the servo's for ailerons when you build it and then just plug them in when you're ready and you've a 4 channel aileron plane.

Get a Simulator as well as it'll make a huge difference with orientation.