White Destiny from Pretear. Morning Grace from Princess Tutu and Aiyaa Four Thousand Years were my two topo, início candidates, but since they're taken, I'll go with my current favorito song. I mean, just listen to it! This song is the reason I adore Yoko Ishida(she sings it, btw)!<3333 Pretear is the only animê I've ever watched where I didn't start skipping the intro after the first few episodes.
Another animê song I really amor is Brothers from FullMetal Alchemist. Vic Mignogna's English version is just so gorgeous, I can't even begin to explain it! It's even sadder if you've seen the animê and you know what Ed's been through... T~T
Brothers:
link White Destiny: