Sorry if it came across as condescending; I'm just tired of the lazy "drugs are more dangerous than tobacco" argument because it's easy to repeat, but essentially meaningless. Answering your question is difficult because very few countries have legalised 'the most dangerous' drugs.
Let's take Portugal as an example, though. It decriminalised heroin in 2001; for the sake of argument, let's agree that heroin is at least very slightly more dangerous to the individual than tobacco. Portugal now has a way, way lower incidence of death due to overdose than almost every country in Europe [1]. That's not relative to numbers taking heroin, that's relative to the population, so even if heroin use has rocketed (which it hasn't; lifetime use has increased from 0.7% to 1.1% [2]) lives have still been saved overall.
Let's take Portugal as an example, though. It decriminalised heroin in 2001; for the sake of argument, let's agree that heroin is at least very slightly more dangerous to the individual than tobacco. Portugal now has a way, way lower incidence of death due to overdose than almost every country in Europe [1]. That's not relative to numbers taking heroin, that's relative to the population, so even if heroin use has rocketed (which it hasn't; lifetime use has increased from 0.7% to 1.1% [2]) lives have still been saved overall.
[1] http://www.independent.co.uk/news/world/europe/portugal-decr... [2] https://en.wikipedia.org/wiki/Drug_policy_of_Portugal#Observ...