Bach, Beethoven, and Brahms. The three "B"s of German music, and everyone has a favorite. That doesn't make any one superior to another. They just appeal to different tastes.
Me personally, I prefer Bach but will not disparage any other composer. Any one can bring beauty into peoples lives and that is laudable.
But, Bach WAS a tremendous organist in more ways than one.
He sired twenty children, ten of which lived to maturity. The most famous was C.P.E (Carl Phillip Emanuel) who went on to become a composer in his own right. Good, yes, but he didn't have his fathers gift. He did gain a bit of fame, though.
JS had other children who went on to greatness but never received the fame of CPE.
On son went into accounting. That was CPA Bach.
Another became a notorious tax collector. That would be IRS Bach.
It is not about disparaging any other composer or musician.
It is all about giving J.S. Bach his due in creating the musical world we know today. It was Bach who basically created to sound world we have inhabited since. Prior to J.S. Bach music was in the so called "mean tone." This was difficult to use. Basically what Bach's "Well tempered tone" tone is all about was splitting the difference in pitch between the frequency intervals of the notes of the octave. That is what his book of compositions in the Well Tempered Clavier is all about. It is basically the instruction manual in how to compose in this system.
The thing to remember about J.S. Bach and be grateful for his life, is not just his music, but his huge contribution as innovator and above all teacher. He could play every instrument except the lute. He was a virtuoso on keyboards, especially the organ, the violin, cello and oboe.
Add to this his enormous and varied output that has greatly and profoundly influenced all who came after.
Not only that, but Bach understood the mechanics of the organ, and was known to be hands on. He was called upon to specify and test organs. Organ builders were known to quake in their boots if they knew Bach was coming to test their creation. Bach's famous Toccata and Fugue in D minor, was almost certainly written as a torture test for new organs. Incidentally it also is probably the best single test piece for audio systems, all the way from subs to tweeters and including power amps. His writing will distinguish peak from continuous power in a hurry. That is because he was testing the organ "windage".
Therefore it was not surprising that polls of professional musicians and music lovers, voted Bach the composer of the millennium in the year 2000.
Irv has mentioned the Beethoven piano sonatas. This is one of the most important bodies of work in all music. However the ghost of Bach hovers over the scores. And like Bach, Beethoven was writing for another time, and said so.
A really good example of Bach's teaching over Beethoven is his variations, on Rule Britannia. This
tune has been a show stopper, when it was written for a Masque on Alfred the Great by Thomas Arne in 1740. Beethoven, never one to pass up a good tune wrote variations for piano on the tune. You can just hear Beethoven saying to himself. "What would old J.S. Bach have done with this". Beethoven turns it upside down backwards and every which way. Clearly he had been taught well and it is obvious by whom.
Another classic is the justly loved Rachmaninoff Variations on Theme by Paganini. What is done with this simple theme by Paganini is right out of Bach's instruction manuals! Examples like these though are just legion and are huge part of J. S. Bach's profound influence and legacy.
The other thing about Bach's music is that it shines though the most outrageous treatment and arrangements of others. However I think that is what he intended.
The only people who have done Bach serious harm has been the older generation of professional musicians who have tried to impose a wholly unwarranted rigidity on Bach's rhythms. Whereas as Sir John Elliot Gardener has been at pains to point out, Bach's rhythms are intended to be highly elastic and frequently based on dance. Sir John is one in a long line of late 20 century and early 21st century performing scholars who have done so much to release Bach's music from so much harm from misconception. The worst is that Bach laid out his scores based on mathematical principles. That is now totally debunked. Not that Bach was not organized at his work bench he was and had to be.
Sir John considers J.S Bach the greatest musician who ever lived. He says so and makes the case in his Biography of Bach, "Music in the Castle of Heaven."