I highly doubt they are going down the vote list.
The P-39 makes sense for a number of reasons, including the incredibly close vote.
The next aircraft added is almost certainly not going to be American and very unlikely to be British.
My guess is something off of this list, and yes, I am giving myself a large target.
Fighters:
C.200
I-16-24
J2M3
Ki-43-II
Ki-44-II
LaGG-3
Me410
Yak-1
Yak-3
Yak-7
Bombers:
Do17
Do217E
G4M2
He111
He177A-5
Ju52
Ju188A-2
Pe-2
S.M.79-II
Tu-2
Wellington Mk III