I am not picturing what you want to do. Rotate? On which axis? Are you building a rocker, circular shaker or vortex spinner? How will your cylinder be attached? How fast does it need to spin?
A brushless motor is easy to manually reposition if no power is applied. The problem with servos is that the are geared and manual movement can strip the plastic gears inside. Stepper motors may or may not be geared.