Is tea tree oil or witch hazel more effective for getting rid of zits?

Neither works well: Both will disappoint you. This is the 21st century, you've worked hard, and you have a right to someting effective. I start with topical Clindamycin with or without a retinoic acid derivative. If this isn't enough, add oral Erythromycin or tetracycline as appropriate for the person. Dermatologists have even stronger stuff. Good luck.