Which essential oils are best for acne?

No oils for acne. There aren't any oils we would recommend for acne sufferers. Oil overproduction is one of the causes of acne, and we look to reduce that oil to help it. Isotretinoin is one of the best medicines for acne and works directly on oil production. Using it as a low dose can eliminate breakouts, make hair less oily, and make life great for a lot of people.
Myth but use if help. Many of my patients swear by the benefits of tea tree or bio-oil and so i generally don't dissuade them but there is very little science to support its use. It is probably the massage, (which we know helps scars) that is used to apply the oil, which is actually providing the improvements observed. Massage with any clean oil 3-4 times a day. Silicon gel trips are morel likely to improve the scar.