These aren't in my top 15 necessarily but with a quick scan they didn't catch my eye:
Alexi Murdoch
Anjelique Kidjo
Carolyn Wonderland
Brett Dennen
Teddy Thompson
Radney Foster
Gomez
KT Tunstall
James Hunter
Ozomotli
Nickel Creek
Jakob Dylan
Ryan Adams
Kasey Chambers
Gabriel Y Rodriquez
I'm sure a few are previously mentioned but just to expand the list.
Alexi Murdoch
Anjelique Kidjo
Carolyn Wonderland
Brett Dennen
Teddy Thompson
Radney Foster
Gomez
KT Tunstall
James Hunter
Ozomotli
Nickel Creek
Jakob Dylan
Ryan Adams
Kasey Chambers
Gabriel Y Rodriquez
I'm sure a few are previously mentioned but just to expand the list.