Me-163!
Ok, not likely, but it would be a hell of alot of fun!!! Make it 500 perk points to fly it.
As for the planes, my personal pet project I want in AH plane is the Ki-44 Shoki. However, realistically, I just want to see the early war plane sets filled out for scenarios and the CT.
However, to NOT neglect gameplay in the MA, I would like to see the He-177 and Me-410 for the Luftwaffe, The Mossie B.Mk.IV for the RAF, a Cant.1007 and the Re.2000/2001/2002 series for the 'Reggia Aeronautica?' (Yikes, I don't remember the name of the Italian Air Force, I know you guys will straighten me out!

-) We know the Japanese Force (IJA/IJN)are getting the Peggy, so I think they need an Attack Bomber more than anything (Jill, Judy, etc). That leaves the VVS and I think the Tu-2 would fill out their ranks enough with their current planes. That's how I would 'balance out' the planeset for MA play (In terms of those dedicated to specific countries).