BFs are definitely up there with queens and emperors on agression. But for your tank, it's the fish i would go with. They are awesome! Once mine hit that 6" mark his agression increased a lot, make sure if you do multiple angels its the last.
Regals are awesome too, just get one thats eating at the LFS. We have been very lucky with the regals that have come in lately, all eating well out of the gate.
Flagfins are great too, and mine never exhibited agression toward anyone but themselves, which was minor. Hardy, flashy, stay relatively small and do well with more than one in a tank.