Oooh, good question! I always believe I don’t care for individual singers until I actually think about it...
Off the top of my head, I’d say Sara Bareilles (inb4 all the gay jokes, her songs speak to anyone’s heart regardless of sexual orientation), Michael Buble (see previous comment), Aloe Blacc, Jack White, Nina Simone, Charlie Crockett, Dolly Parton, Dave Grohl, Haley Reinhart, Leon Bridges, Melody Gardot, and probably some more that currently escape me. I realize some of the aforementioned also/primarily play in bands, but I still enjoy their singing voice quite a bit.
What about you, big dawg?