My signature tune is Angels by Robbie. It's a song that is much harder to sing than you may think but it's one I really give it my all for.
Had many standing ovations for it over the years which is quite humbling when playing pubs.
If you have any kind of a singing voice this song isn't too vocally challenging. I have sung it many times when I was gigging. Give it a try on the karaoke if you get a chance.