Formal:
* Provoke: This is a direct synonym, meaning to incite or stimulate an aggressive reaction.
* Harass: Implies a more persistent and often hostile attempt to annoy or upset someone.
* Bait: To deliberately provoke a reaction, often with the intention of making someone angry.
* Incite: To encourage or stir up a hostile or violent action.
* Aggravate: To make a situation worse, often intentionally.
* Alienate: To cause someone to feel isolated or estranged.
Informal:
* Pick on: To target someone repeatedly with teasing or bullying.
* Get to: To annoy or irritate someone to the point of frustration.
* Rub someone the wrong way: To behave in a way that is irritating or offensive to someone.
* Wind someone up: To deliberately provoke someone with the intention of getting them angry.
* Push someone's buttons: To deliberately say or do something that you know will irritate someone.
The best synonym for "antagonizing" depends on the specific situation and the tone you want to convey.