I'm going to vote for Till I Collapse. My personal favorite, that song got me through alot of hard times in my life.
Still Don't Give a Fuck is another song that saw me through some shitty times.
People like to focus on the negative in Eminem's lyrics, but fail to see exactly what it is about Eminem's songs that so many people can relate to. He says what alot of people think, so when you pop in a CD, and you're having a bad day, and you hear him start rapping and it's like he's telling your story, that's the kind of shit that actually SAVES lives in the long run.