Never have done benzos....I'm on the tail end of the sort-of hippie generation and did not do pills because they weren't "natural." (insert rolly-eye emoticon here.)
Nicotine, for me. I've been able to quit drinking many times, longer than I could quit smoking. But alcohol is different - 20 years ago my addiction to nicotine was the same level as now. My addiction to alcohol (took me a while to realise the truth of it being a truly "progressive" disease) has become a much tougher nut to crack. If I stay sober for a while longer, I hope to have the confidence to quit smoking too!
Used to smoke pot daily, did a lot of various kinds of speed, acid, have tried heroin, done opium more than once, shrooms and angel dust many times, cocaine...either I simply didn't get addicted or I didn't do some of these substances long or often enough to get addicted to.
I spent a weekend many years ago shooting up meth. Coming down was the most horrible thing and when I caught myself contemplating doing some really degrading things just to get more, I scared myself straight, pretty much.
I do find it sort of ironic that of all the illegal substances I have used, it was only the two legal ones - nicotine and alcohol - that I got addicted to.