Many likes the Queen's design the most.
I think the Hydralisk, Corruptor, Mutalisk, Broodlord, Drone, Queen, Nydus worms (I know it's a structure but it's awesome nonetheless), Zergling, Roach, Infestor, Hive (building), Greater Spire (building), Overlord, Overseer, Baneling Nest (building) and Banelings are awesome.
Wait... That's almost all units... T_T