Second iteration of the "flame" one works for me the best, with some tweaks on where the light is coming from. The "cross" version is a bit offensive to me. What is it's message: implying Christians kill people like smoking does, or something to the effect? Or maybe the Jews killed Christ like cigarettes kill people? It's unclear and kind of extreme without direction of where to put one's tugged on emotional distress. The "skull" version is OK, but is kind of passe - seems like skulls are everywhere now so there's not really a shock value. The "jail" version would have been pretty cool, about 30 years ago before it was already used as a metaphor for addition/smoking/etc - they have been done before to one extent or another. I think your original idea with flames is good, just stretch yourself and mold the idea a bit more. IMHO, good luck.