The next one is a special one. Oddly enough it is never one of the songs I think about when asked to name my favorite track(s).
Nevertheless it is without any doubt the song I have found myself singing or humming to myself most often, and I still do it on average once a week. No other song comes even somewhere near that. So it must have something my brain likes :-)
It is Kosmonova's "Singin' In My Mind" featuring Tania Evans of Culture Beat fame:
It was also covered by Paris Avenue in 2005.