Clinically proven medications such as nicotine replacement therapy, bupropion and varenicline are available to help smokers quit but there are not widely used. The primary objective of this study is to evaluate the real-world long-term effectiveness of of bupropion and varenicline treatment in a community sample of smokers interested in quitting. The investigators hypothesize that varenicline treatment will result in higher quit rates at end of treatment and at one year after treatment compared to bupropion. Smoking status will be biochemically confirmed at various time points using salivary cotinine measures. Furthermore, since 50% of the variation in quit success is genetically determined, and the effectiveness of different cessation medication may differ considerably in sub-groups of smokers carrying certain genetic variants, the investigators will collect saliva samples from consenting participants to evaluate the moderating effect of genetics on treatment response.