Messerschmitt Me-262: perhaps the finest all-around World War II aircraft and almost undoubtedly the most exciting one of those that were realistic.
Unlike the Me-163 and so many others that were flawed, the Me-262 seems to have been a wickedly excellent weapon. Fast, revolutionary and hard-hitting. It paved the way for jet age of the fighters to come and signaled the beginning of the end for piston fighters. The Gloster Meteor helped too, of course.