This topic has been conversation between me and my friends quite often. I always talk about who I'd use for sessions, when I'm focused more on producing.
First call guys, for major mainstream artists(depending on artist and material)
Terry Baker
Joel Smith
Jeremy Haynes
Calvin Napper
Mike Clemons
Rex Hardy
Pudge/Spanky(I'd love to use either of these guys on a project, outside of G.A)
Also, some newer guys, but great session players
Allen Mabson(Terry nephew)
Mike Reid(D.C.)
Diante Johnson(Chicago)
Just to make it interesting, what about guys that don't usually play gospel
Derico Watson
?uestlove
Todd Sucherman(I'm sure he'd nail some nice ballad stuff)
Paul Leim(church type tune maybe)
Keith Carlock