I like the Wilburn Brothers' and the Phillips Sisters' warm and welcoming faces:
And The Crossroads Quartet:
Here are some Season's Greetings, country-style:
And some righteous-looking dudes:
As Lauren helpfully points out, rudimentary biographical information on a few of these artists can be found at Hillbilly Music, but many of the details are lost to time. Until the next heartfelt archivist researcher digs them up, that is.