This ain't a what's your favorite, or what's the best Eminem song. What do you consider is the most "epic" song he has made?
For me I think it would be Underground. I love how "cinematic" this whole song is. The production makes it sound as if it was the climax or "end battle" of something, and the lyrics sound like a twisted nightmare that's taking place in Em's head, fighting against horror movie characters. Yeah.
Other "epic" songs: Cinderella Man, Till I Collapse, Soldier.