Can't say I'm a fan of either since I've seen what overdoing it with both can do to a person. :/ But if I had to choose, smoking is far worse, generally with drinking, you can keep the effects to yourself, smoking tends to hurt those around you as well.
Really they're both pretty damn bad for you; the effects of cigarette smoking are just more obvious. I would say the majority of lifelong smokers don't get lung cancer, and if they do it doesn't metastize. I've known smokers that have lived to be 95 and drinkers that have died of alcohol poisoning or drinking-related accidents at 17. It's all pretty individual.
I don't do either as I'm fairly health conscious (not to mention substance use is athletic suicide) but if I were to do one it would probably be smoke.