I don't have an exceptional amount of experience, but our "midas" and our chocolate cichlid are both mean-tempered, angry, vicious, and very very territorial.
Our "midas" has killed/eaten/battered several fish so that "he" now has his very own tank (with nothing but sand and driftwood as he destroys anything else). No matter how well we thought we planned his tankmates, the "midas" would hunt them down til they were literally too exhausted to swim away and then eat or abuse them til the threat was eliminated - "he" is completely ruthless and unstoppable, cold-blooded in more ways than one. After seeing him draw blood on more than one occasion I decided to leave water changes to the hubby....
Our chocolate cichlid is more moody and territorial, more of a bully. "He" mostly leaves the striped raphy alone but ate all "his" dither fish and will attack anything within a foot of "his" tank, whether it be hand, face, or cat....and the way he kills his live food is brutal, stuns it with a quick charge then rips it up. I had heard that chocolate cichlids were supposed to be relatively mild-tempered and even shy cichlids, HMPH!