I can't vote, i like too many of them
In no particular order:
Do-17 and Wellington because bombers are fun.
Defiant for the "wtf" factor and funky multiplayer possibilities.
Beaufighter because multi-role twins are cool. Especially with the interface we 've been given, Mosquito and Ju-88 variants would be awesome in a future add-on. Want to go strafing load up guns, want to go bombing load up a glass nose, this way we can have multiple variants with just one slot of flyable aircraft.
Sunderland and He-115 because i like floatplanes and flying boats.
A lot of the above aircraft also have a history with operations involving radar, which is another of my long awaited for features in a WWII sim. While i don't fly modern sims because there's too much avionics work, the thought of hunting U-boats in a Catalina through the mist or chasing bombers in a night fighter with primitive radar equipment is something that i always found appealing, it would be like a cross-over between flight sim and sub sim due to the "cat and mouse" game involved with those early sensors.
And if you want to go really hardcore, think about flying a radar equipped Swordfish Mk.III in the convoy escort role
