Menthol, Mint, and Cinnamon are the strongest flavors. I'm not sure what kind of "buzz" you think you are getting, but generally speaking too high of a nic concentration can make one feel a little loopy or odd.
How heavy of a smoker are/were you? Basically, how many cigarettes did/do you smoke a day? 18 mg is generally recommended for a pack and a half smoker.