The question can't be answered without knowing the application parameters (rotational speed, torque, acceleration profile, acceptable size). Generally, DC motors (conventional or brushless) can be expected to give the highest effiency and specific power. From your description (e. g. adjustable angle range), I expect that your actually needing a drive with a gear rather than a simple motor.
Also a conventional DC motor can be operated continously for hours, but it has a limited total lifetime of some 1000 hours, while brushless DC or stepper and AC motors have a life expectancy of many years.