In no particular order:
Josh Groban, Judy Garland, Helen Reddy, Karen Carpenter, Charlotte Church, Doris Day, Marie Brennan, Amy Grant, Dean Martin, Elvis, Adrienne Camp, Andrea Bocelli. I'd list singers from Tourniquet, Rhapsody, and Narnia, but I haven't the slightest idea what their names are and I'm too lazy to look them up. The same goes for the Japanese music I listen to - I just sort of latch on to individual songs rather than the singers.
For DJs (they don't sing, but they don't really count as bands, either) I like DJ Mystik and DJ Tiesto.