For too long, TVB has promoted its actors and actresses to sing theme songs for its dramas and most cannot sing. That's what made the theme song to The Hippocratic Crush all the more appealing. Cantopop queen Joey Yung has just the right powerful voice to deliver this song. I loved it after listening to it just once.
Another song is the sub theme for OL Supreme. Denise Ho is an excellent singer. (Btw, I'm a Goocho fan.)
A classic that I can't get enough of is the subtheme for the 2002 adaption of Journey to the West by the Monkey King himself, Dicky Cheung. Such a fine, soothing tune.