ORIGINAL: TFF
I think you are discounting how good the Sig 1/6 , 1/4 and BUSA kits are for being scale. What is wrong with them can be easy to fix for some one who wants to. It would be much harder to start with the 1/5 sig, GP or Goldberg, as good of airplanes as they are.
That's interesting that you say that, because I had always assumed that the 1/5 scale SIG was "better" that the 1/6 scale version. Maybe the 1/6 scale SIG at about $90 is what I should get.
After looking at a build thread for the 1/6 scale Cub on RC Groups, you're right that that one looks like the kit for me!