Tripping is the one most affected - more high level enemies can fly or are really big. However, by 9th level any combat maneuvers are only useful if you've put a few feats in. Just the brawler maneuver training isn't going to be enough.
If you have then grappling or dirty tricks are good. The combat maneuver most used by monsters is grappling, the CMD bonus of maneuver training may be useful there even if you're never going to use grapple offensively. Disarm is useful against the right enemies. Overrun can be useful iff you have charge through.