Evanescence have been my favourite band since 2003, the very first song I heard from them was "Going Under", though it is no surprise that it's one of my favourite songs from them; I find Amy Lee's vocal range and haunting vibe admirable, and it stands out very well in that song. Though I really haven't been keeping up with their recent material to know which songs post-Origin, Fallen and the "Special 2004" album catch my interest.
Though picking favourite songs from them is very...difficult, because I love almost all of them. But if I had to list...hm, Going Under, Bring Me To Life, Everybody's Fool, My Immortal, Imaginary, Hello, Taking Over Me, Whisper, Fields of Innocence, Exodus, I Must Be Dreaming annnd Understanding.