My favorite fighter would be the Sopwith Camel. But my love has always been with the bombers. I love the Handley Page O/400 as well as the German Gotha bombers. The zeppelin bombers are pretty cool too with the special "height climber" zeppelins that could reach over 20000ft.

My favorite aircraft of all time is definatley the B-29 Superfortress of WWII. The earlier models were ok but the later B-29B's and the Silverplate Superfortresses were extremely technolocially advanced and could do over 400mph.