You may want to look up some web pages of the choirs that exclusively
sing Bach.  Here in Saint Louis we have the American Kantorei and the
Bach Society of Saint Louis.  Many of these soloists, especially in the
Kantorei, have sung many of the cantatas with different choirs around the
world, some are even recorded.  Though it may be on more of a
local/regional level, this may be some help to you.

Stephanie