[Marwan]

In terms of "Widely appreciated" regardless of genre and likes or dislikes, I can see something like Jeff Buckley, but NMH? I like them, but I don't think they'd fit in due to the lead's voice and the fact that they have more of a niche sound.. I'm not sure if I completely understand what OP is asking for though.. As with other threads, anything involving the Arts is really subjective.. I look at Jackson Pollack and see splatter that I think I can do, others see a work of art.. same with songs really.

fwiw I like the Nina Simone suggestions the best so far.