Which is more effective, laser acne or micro-dermabrasion?

Depends. Laser acne treatments usually target sebaceous oil glands and help to damage/reduce them. They also help acne scarring by stimulating new collagen growth and by helping to reduce brown and red areas. Microdermabrasion removes the top dead layer of skin and also helps with red acne scars and promotes milder collagen stimulation. In my practice, i often combine the two procedures for synergy.