Dont get the ball type movement mounts. Its very hard to align those and tighten at the same time. Every time you hold it in position and tighten the screw, ball joint just changes its orientation. And they are not very sturdy.
Get the mount with arms, which can adjust and fit any projectors. I have this mount, its very sturdy and rated for 50lb Ceiling Bracket for Projector (Max 50lbs) - Monoprice.com
