Mostly in order
My mum. I doubt there would be too many days in last 33 and a bit years when I have not heard her singing. And if there has been a day when she hasn't sung with voice, there hasn't been one when she has not sung with life.
A girl from Sunday school at old Church. 10yr old, what a voice. She was always keen to learn about God and make sure she had it right. I pray she will continue and I'll be able to buy CD in a few years.
4 friends of mine. (Means what it says, not a name of a group.)
Any choir that does Handel's Hallelujah Chorus, or almost any hymn (see the Hymn-Makers series of CDs)
George Beverly Shea. He wouldn't have made the list when I was growing up. I know better now.
Keith Green. Even though now and then he fell into the trap of writing a "what was all that about" song, when he wrote and/or sang a good one, incredible.
Honourable mention to Annie Herring for Heart Of Stone.
Petra are a group, not a singer, so I won't mention them. Whoops, too late. Well, while on topic of Petra, I think a mention deserved for songs like Creed & Love.
Now at the other end of the scale:
I had listed a couple here, but on pondering the names I had to doubt wether I could include them as Christian singers (or be nice when writing about them), so will just go on to...ME! I sing like a frozen cat playing the bagpipes in a blender full of gravel that's being cut in two with a chainsaw...Thankfully my guitars sound a little better than that...(sometimes...)
Pete