Depends on the situation..
Sharks, Pirhanas, and Puffers all have a big bite, but not the personality to be deemed 'aggressive'.. just predatory.
Dovii, and Buttikoferi are very rowdy cichlids..
but nothing compares to the mentality and jaw-structure of a Channa.. wolf fish, and many others don't have this instant killer instinct nor the razor sharp jaw-line to rip, shred, and destroy..
Snakehead, hands down.. have had this conversation before.