Politics aside, I'd choose to fly allied aircraft. I'll admit to wanting to fly different planes in different times and or theaters of the war. Not to mention different missions.
I'd love to fly a Hurricane or Spitfire durring the Battle of Britan. I can think of no finer point defense fighter than a SpitfireXII. For long range fighter escort , in europe, I'd take the P-47D or P-51D, in the pacific I' choose the P-38J or the P-47D. For operating off a carrier I'll go with the F6F-2 Hellcat, or maybe the F8F-1 Bearcat. Althought the Bearcat really never saw any combat in WWII.
There is ofcourse the Mosquito. In my oppinion the finest multi-role twin-engined aircraft of the war. The only thing to come close to the Mossie would be the Douglas A-26 Invader but again the A-26 barely saw service in the war.
Bomber wise I'll go for the ultimate. The B-29. But for europe I'll take the B-26 for a medium bomber and the B-24 for the heavy. Of the British offerings I've always liked the Shorts Stirling and the Halifax.
Of the palnes that the Soviet Union had to offer I'd go with IL-2 Stormovik for first choice with either the the Lagg-3 or the Pe-2 coming in as next choices.