Stay: Look on the bright side--if your boss did know everything you do, you’d probably feel underpaid and unappreciated. Keep a positive self-image and realize no one will ever know how good you really are. Do your job well and leave time for volunteering -- where people truly appreciate you.
Leave: Being “systematically” overlooked could cost you dearly when it comes to promotions and pay. Staying on makes no sense for a wallflower who could be blooming in a new job. If office politics is making it impossible for you to thrive, find a job where your talents and potential will be recognized.