Amphetamines (esp meth) and Temazepam.
I still use amphetamines, but not meth. And I can't be around temazepam because i'll get my hands on it, other benzos were a minor problem (nitrazepam, alpralozam, lorazepam, clonazepam, diazepam, oxazepam) but not enough for an addiction, temazepam was leagues ahead of all those and cost me alot. Overall? i'd say amphetamines, with temaze a close second.