Ray Bayless, who initiated this thread, is correct that there are so many
recordings of Bach's cantatas that it can be very difficult to make
selections.

The most popular of the cantatas are BWV 4, 21, 51, 56, 140, 147, 202, 208,
211, and 212.  I find that the quality of Bach's over 200 cantatas is very
consistent, and I would not personally recommend limiting oneself to just
the cantatas listed above.

As for particular sets or recordings, I don't know how much money Ray
is willing to spend.  Some other list members will likely provide
recommendations on modern instruments.  I'll restrict myself to HIP
recordings:

1.  Two current cycles going strong are Suzuki on BIS and Koopman on Erato.
Overall, I favor the Koopman cycle, and its price is a little lower than
Suzuki's.  I would recommend starting with volume 4.  The first three
volumes included Barbara Schlick, a soprano who is definitely an acquired
taste.  The Koopman series is now up to volume 7, and each volume has at
least 3 discs.

2.  My favorite Bach cantata conductor is Herreweghe on Harmonia Mundi.  He
has recorded quite a few discs over the years.  Ray could not go wrong with
this series.

3.  A less expensive proposition would be Rifkin on Decca/L'Oiseau-Lyre.
The few recordings Rifkin made are now available at mid-price.  The
performances are excellent.  If I think that Herreweghe is better, it's not
by much.

4.  Some folks swear by Gardiner who has recorded a few discs on Archiv.
I find both Rifkin and Herreweghe superior.

If I was starting off, I'd go with a combination of Herreweghe, Rifkin,
and Koopman.  However, whatever route Ray takes, he's in for a great time.
Just be sure to have your credit cards ready.  I only have one credit card
these days; you can easily figure out why.

Don