One big decision is do you want to fly only?  Or is building as much a part of the hobby for you as flying?  Building is time consuming.  ARF's and RTF's eliminate that time.  I personally get alot of gratification from building my own from kits.  If you bought everything you needed to build a trainer a/c kit it might take you a month of dedicated time in the evenings to be ready to fly.  I am building a kit that I started back in early Dec that I will not finish until March.  Of course I have not worked on the kit daily.  Many days have gone by with me doing nothing at all.  But I paint my models and I need good weather to do that.  So how much time do you have?  </p>