I think this is a really difficult question. I would tend to vote for either Marten or Dora, but I feel like Marten's parents, as unusual as they might have been, were more caring about him than Dora's parents about her.
And about Tai:
I doubt that "hard drugs" is the right term for Tai's usage. Pot wouldn't qualify as a hard drug, and while LSD would, it doesn't make you addicted at all. It just messes with your subconsciousness. I would even see using LSD as prove for her not having a hard childhood. Using LSD when having bad, maybe even suppressed memories would fuck somebody up severely.
If somebody would abuse drugs to cope with a bad life it would probably rather be some kind of opiate, Heroin, Morphine, something like that. Or Methamphetamine (Meth), Cocaine or Crack. But not LSD.
Also keep in mind that I know all this from books, wikipedia and a few internet forums with people who are abusing drugs, so it could as well be wrong, but I'm rather sure about this.
I wouldn't dare using something that addictive or damaging ones subconsciousness.