it is really draining having to watch favoritism at work

Think I might have to quit my job of 4 years soon, favoritism is rampant there and there isn't any room for me to grow so why stay? People who just started last year are already getting promotions and that's because they either kiss ass or are buddies with the supervisor. One job in specific I should have definitely gotten but they didn't post the job so I didn't even have the opportunity to apply to it. They just gave it to someone they chose. The favoritism is really sickening at this place