I have a thing against repetition, too, so even the songs I love become otherwise if I listen to them too much. The radio (how quaint!) has ruined many a song for me this way. (This is potentially a problem with a small child who is all about repetition, but that's neither here nor there.)
But not answering at all is a copout, so here is my right-now answer to this question, with signs posted about the right to change my mind as often as I want.
[...tick...tock....tick...tock... This is harder than I thought, coming up with one song I'm willing to claim as my favorite. Even just a favorite. I'm back to "this is ridiculous," but still want to choose something... tick...tock...]
Ok: "I Will Survive" by Gloria Gaynor. Of all the songs that ran through my head just now, this is the one that I cannot listen to without singing along, without turning up the volume, without getting up and dancing/acting out. Many other songs are better in many ways - I wouldn't actually want to listen to this right now - and I know I didn't even think of many songs that would live up to the label of favorite, but it'll do.
And hey, maybe the underlying empowerment message would get me through the dark days under that lone palm tree.