RE: Which combat plane
I guess the easiest answer would be the one most people fly in your area, or at your field. There is nothing like experience when it comes to setting up a new plane that no one around you is familar with. Are you looking for something to use for informal combat, or RCCA Class-B?
Do you prefer Wings or standard airframes? There are alot of good kits out there, but it again boils down to what your looking for...