Starscream, just because he's so hilarious.
"Megatron is in the bathroom, now _I_ lead!!!"
"Megatron has stubbed his toe, now _I_ am the leader!!!"
"Megatron fell asleep, now _I_ rule the Decepticons!!!"
Funny thing was that the Decepticons would just shrug and follow him.
Close runners up--Ultra Magnus and Optimus Prime, just because they have the pimpingest names.
