Well, Frozen's Let It Go is pretty high up there. Idina's version, anyway.
I enjoy Elton John's rendition of the Circle of Life. When the movie was out back in '94, one of the local Pop stations played, quite frequently, this really, really wonderful combination of both the movie version and the Elton John version, trading off verses and the chorus between each one, and it was amazing. I don't think it was every made available anywhere outside of radio and that's just sad.
Beauty and the Beast is just awesome. Done in the right setting, it can bring a tear to my eye at the climax.
Supercalifragilisticexpialidocious is lots of fun too.
That's all I've got just at the moment.