As for the WWII Bombers, My favorite of the heavies is the Lancaster. For the medium stuff, its a toss up between the Mosquito and the Petlyakov PE-2, while technically both bombers, they were so versatile they trully are a challenge to pigeon hole.
For the postwar stuff, who couldn't fall in love with the English Electric Canberra on sight? In the tradition of early postwar design, where streamlining was so critical to compensate for lower power engines, she struck a near perfect balance between effectivness and design aesthetic. If the Mosquito ever had a post war heir, the Canberra is it.
Lets hear it for the Canberra, the oldest still active bomber design in service and the only combat aircraft anywher to still incorporate wood in its design. Yeah, the BUFF's been around and she's respectable, but the Canberra still has a few years up on her and is still better looking. Who says older gals can't still be sexy? :-)