Favorite song is hard for everybody. Personally, I don't have any ultimate ones. I go through moods and feelings... and since I'm young I go through ages and phases. Right now my favorite songs are...
What Difference Does It Make, by The Smiths (quite simply because Morrissey is one of the greatest lyricists in the world)
Politicians In My Eyes, by Death (no, not the metal band. All African-American proto-punk band from the early 70's)
Jolene, cover by The White Stripes (Specifically the Blackpool lights performance)
Nightcall, Kavinsky (Might know it from the film Drive)