There are people who say they would rather have Bach and no one else than everyone else and no Bach. I am not of that camp but I can understand where those who are might be coming from. There is something about Johann Sebastian that answers every musical need from profound contemplation to intellectual fascination to, last but not least, toe-tapping danciness. I have known and loved Bach since I began exploring classical music seriously and among the first classical recordings I bought were performances of the Brandenburg Concertos and some harpsichord bits and pieces.
Until recently I had a couple of dozen of Bach's cantatas on CD and had heard maybe a dozen more but I only set about listening to the whole lot a few months ago. There are over 200 if you include the secular cantatas but the great majority are on religious themes and the texts are often deeply touching. But the music is the thing and I have been astonished at the non-stop stream of creativity and inventiveness Bach shows in these pieces. Although there is the odd instrumental sinfonia they are mostly based on the format of choir, recitative, aria and choral. Some are for one voice, some for several and there are a range of obbligato accompaniments in the arias, usually violin, oboe, cello, flute, trumpet but other instruments too. Within the relatively restricted language of the 18th century baroque Bach never seems to repeat himself. His melodic inspiration never fails and he brings out the meaning of the text with unmatched skill and emotional depth. Without denying the marvels of his keyboard, chamber and instrumental music or the wonders of the B minor Mass and two Passions, I have now come to the conclusion that it is in his cantatas that Bach's musical genius is best displayed.
There are several complete recordings but I have collected them from a variety of performers, the famous Harnoncourt/Leonhardt recordings with boy choirs and sopranos, and those of John Eliot Gardiner, Ton Koopman and Masaaki Suzuki which are all excellent but I rather like the budget priced edition of Pieter Jan Leusink with female sopranos and the Holland Boys Choir which seems to capture the Lutheran idiom very well even if it can be a little rough vocally in places though that does give it a certain homespun authenticity such as one might imagine you might have heard in the Thomaskirche in Leipzig which is where Bach composed the bulk of his cantatas when he was the Kantor or musical director there from 1723 to 1750 though most of the works were composed during the first few years when he would sometimes be turning out a cantata a week for the appropriate days in the church calendar.
The cantatas are referenced by BWV numbers starting at BWV 1 and going up to BWV 215 though a few in that list have turned out not to be by Bach. The last 15 are secular and the rest spiritual. I think it would take you several days to listen to the lot and that's if you carried on day and night so here are some of my favourites which you will be able to find in decent performances on Youtube. I've deliberately left out some of the more famous ones such as BWV 147 which is the Jesu Joy of Man's Desiring one.
In that list BWV 4 is the first he wrote around 1707 and BWV 30 among the last in 1738 but the great majority were written in Leipzig between 1723 and 1726 in what must have been one of the most extraordinary bursts of creativity by anyone ever.
All the performers I mention above use period instruments but slightly older recordings were those of Karl Richter and I have a soft spot for these because of the excellent solo singers and spiritual insights of someone who actually served as the organist of the same Leipzig Thomaskirche where Bach had been musical director for 27 years. Also because among the first classical music records I bought was an LP of highlights from the St Matthew Passion conducted by Richter and I still prefer this to any version I have heard since, especially the aria Mache dich, mein Herze, rein (Make thee clean, my heart, from sin) sung by Dietrich Fischer-Dieskau. Listening to this really does leave one feeling spiritually cleansed, for a while at least until the world closes back in again.
Mache dich The aria start at 2.35.
You might wonder why in a post about the cantatas the only musical link I provide is to an aria from the St Matthew Passion but the musical language in the same in both genres, and there are just too many superb arias in the cantatas for me to be able to pick one or even several. This was among the first Bach arias I ever heard and it remains special for me for that reason and also for its great spiritual beauty.