I find that there are actually quite a number of ATV actors that can sing well. The ones I feel can sing well are
Andrew Yuen Man Kit
Crystal Tin Yui Lei (ex-ATV)
Benny Chan Chin Pang
Pinky Cheung Man Chi
Raymond Wong Chi Yin (sometimes ATV)
Kenneth Chan Kai Tai
Amy Chan Sau Man (sometimes ATV)
I wonder why ATV didn't let Andrew sings more themesongs. I've heard him sing the subtheme of The Snow Is Red. He has a good voice and his singing was already pretty good back then. He was able to bring out the sadness of the song very well. I actually wanted to cry while listening to that song. With more polish, he could be a very good singer. His singing talent was really wasted at ATV.
Raymond is also another actor that deserves to have his own album. His rendition of the themesong of Venture Against Time is very good.