What is the best treatment for smokers lines?

As far as the treatment of smoker lines around the lips there are multiple modalities available. I have personally  found a combination of conservative Botox and skin resurfacing to be ideal in this scenario. However meticulous use of fillers can also have a positive effect. 

Smokers lines can be treated with fillers, I suggest Juvederm or Belotero , which is a thick viscous filler and very affordable, It is hard to say how much you would need with out pictures or an in person consult, If fillers are not an option i would recommended non ablative laser resurfacing , or deep chemical peels , such as perfect 10 peels, which have multiple series ( beginner , intermediate and advanced )... make sure to see an aesthetic facial doctor , such as a plastic surgeon or dermatologist.

Without photos, it is really hard to gauge how severe your lines really are.  But in general, I would recommend a combination approach including some or all of the following:
Medical Skin Care - to prep the skin and maintain the results once rejuvenatedProfractional Laser Resurfacing - to help stimulate collagen and rejuvenate the entire face (not just the upper lip so that this blends evenly)BOTOX Cosmetic - To help decrease action of the muscles and allow this area to heal more evenlyVolbella XC - to help fill in lines and potentially stimulate collagen Microneedling - to help encourage new collagen growth I hope this helps.