I learned on an Avistar Select with an OS 40la two years ago thanks to Marv at Propmasters RC Club and RCU Now it is mostly flown by my 12 year old daugher on a buddy box. The only issue is that the 40LA isn't that usable for upgrades so I left it on the Avistar. I now flya 40 Supersportster with an OS 46FX. The Avistar was great preparation for this plane. I am finishing a four star 40 (TT46pro) kit to try kit building. I have GP T34 40 (OS 46FX) and VF Edge 540 (Magnum 91) ARFs waiting for assembly this winter. I replaced my Futaba 4 channel with a 6EXA and wish now that I had known the 7C was coming since it has better mixing and programming but the 6EXA is fine.

My take on a trainer is that if you think you will be pretty quick in learning (aka have used a flight sim or play a lot of video games) get a semi-symmetric wing. If not get a flat bottom of the many from which to choose. The MOST important thing is get a good instructor.