My advice to you is, pick which complaint about your skin you are most unhappy with. If it’s pigmentation, then choose a serum for that, if it is fine dehydration lines, then pick a hydrating serum, if it is lines and wrinkles, then pick a serum with growth factors or a serum containing retinol. In your case, you are saying that your skin is acne prone and fairly sensitive, so I would suggest an HA Serum (EG HA Serum from Lamelle) or an anti-oxidant serum (EG Phloretin Serum from Skin Ceuticals).