St John Passion (BWV245, 1724)
My version: Amsterdam Baroque Orchestra/Koopman with Schlick, Wessel, de Mey, Turk, Kody and Mertens (Erato, 1994, 1 h 48 min)
Right from the beautiful opening choir (Herr unser Herrscher), which takes almost 10% of the total playing time, this is a masterpiece that keeps you enchanted for close to two hours. The scale may be less grandiose than its more famous counterpart, but the intimacy works very well, with delicate melodious interplay between recitatives, arias and choirs. The absolute highlight is the (almost) closing choir Ruht wohl ihr heiligen Gebeine, one of his most poignant melodies. If I have one complaint about this work, it is that many of the short choir lines are so beautiful that they end far too soon. Had Bach not gone on to compose the St Matthew Passion, this is the one Passion that everybody would have talked about it. Essential.
My version: Munich Bach Orchestra/Richter with Mathis, Fischer-Dieskau, Baker, Schreier aand Salmimen (Archiv, 1980, 3 h 24 min)
What more is there to say about this masterpiece, one of the greatest compositions of all time? Dramatic, almost opera-like, with some of the most beautiful music ever composed, never a weak moment, and emotionally gripping, even for an atheistic agnostic like myself. Highlights: too many to list them all, but I definitely need to mention Buss und Reu, Blute nur du liebes Herz, Ich will dir mein Herze schenken, Ich will bei meinem Jesu wachen, Erbarme dich mein Gott, Gebt mir meinem Jesum wieder, Koennen Traenen meiner Wangen, and of course O Haupt voll Blut und Wunden. And maybe the very best, close to the end, Mache dich, mein Herze, rein - always gets me close to tears. My favourite composition by my favourite composer. Hors concours, no doubt about it.
My version: Collegium Musicum Tuebingen Chamber Orchestra/Rehm with Lehmann, Kuenstler, Jelden and Schaible (Brilliant Classics, 1990, 1 h 58 min)
Long ascribed to the grandmaster himself, it is now believed that he arranged someone else's composition for four voices, chorus, orchestra, and continuo to meet an urgent deadline for Good Friday in 1730. It does have some typical Bach touches, especially in the recitatives, and in some obviously recycled material from the St Matthew Passion. Only one aria really stands out, for the tenor near the end (Lass mich ihn nur noch einmal kuessen). All in all, it is in quality clearly below the two main passions and most of his cantatas. There is still a lot to enjoy here though - even though it is not vintage Bach (or even Bach at all).
My version: European Union Baroque Orchestra/Goodman with Covey-Crump, Jones, Burrowes, James, Agnew and Tolonen (Brilliant Classics, 1990, 1 h 41 min)
This work is almost certainly by Bach, but almost certainly not in the form it is performed: most of the music has been lost centuries ago, and several attempts to reconstruct it have been undertaken (more information in the wikipedia link). The work as performed has some nice moments, but makes a patchy impression and I honestly had a hard time sitting though it while refraining from touching the "next" button.
Summarizing recommendation, based on my own taste:
Hors concours: St Matthew Passion
Essential: St John Passion
Good to have: St Luke Passion
Not required: St Mark Passion