This magnificent and sublime work stands as one of the greatest musical creations of all time. I do not feel qualified to recommend one recorded version as being the definitive one; there are so many factors. So I will list some of my personal prejudices, preferences and failings in the hope that the answer to which version you should buy may emerge by default!!!
For my tastes, I generally do not choose "period" instruments. Oh, I know that authenticity is very important and that to deviate too far from the original concept is dangerous and can devalue the musical currency, etc., etc. But I believe that most artists, particularly in the days when availability of performers and instruments were limited, would have used more and better if they could, on many occasions; and that they would wholeheartedly have approved of later performances augmenting the size of, say the orchestra, or the range of the keyboard to achieve effects only hinted at by their relatively-limited resources.
Were I to buy this work (I do have a performance on cassette) I would probably choose the Otto Klemperer version with the Philharmonia Orchestra & Chorus.
For an excellent "period" recording, you could try recommended versions by Helmuth Rilling with the Gachinger Kantorei Bach Collegium of Stuttgart. Or another which a good friend of mine highly recommends is Nikolaus Harnoncourt's 2000 (AD) version. At nearly 3 hours, I don't think it is a good idea for you to listen to all these versions straight through at the same sitting (!) but this may give you some direction in choosing a version to buy. One last prejudice...I will offend a few purists here; but only on very rare occasions will I choose a 78 rpm transfer to CD, however good, simply because I DO like good recorded sound. There are magnificent performances from the past which I have to reject simply because my ears, just like technology have moved on; and in many cases sheer brilliance has to be sacrificed just because the recording techniques were so limited.Sorry if I have raised more questions than I have answered; but whichever recording you finally choose, you will own one of the wonders of the Musical World...happy listening!!!
