definately battle rifle from HALO bad looking gun (in a good way) and would definately make from scratch if not that the return of the m82 in a more accurate version
Personally, I would buy a base gun, and then add aftermarket parts onto it after. That is what I am doing right now. My base gun is a Tokyo Marui SR-16, and I am over half way to my goal of 40rps. I'm at 28 rounds per second at 350 fps, and I want a gun that shoots at least 40 =).
My dream AEG would have to be the Avenger Minigun (in airsoft form)
It would be SO sick to walk onto the field and just spray with that thing, however, once you walked out from behind cover you would be immediately shot by no less than 5 snipers. Still, It would be beast to have it.
M14 TM clone with the heavy duty EBR kit (I think it's made by G&P) all upgraded internals (I have mine up to about 410 fps) with two LiPo 11.1 volt batteries and a IR scope.
I'd get a Systema with all the goodies....the only reason its a "dream gun" is because I can only DREAM of shelling out that much money for an AEG...hahahha...who knows, with as much money as I've spent on airsoft already, Im sure I'll own one at some point.