The standard scholarly study of [tuning], Murray Barbour’s 1951 Tuning and Temperament, opined that Bach’s organ music “would have been dreadfully dissonant in any tuning except equal temperament”—not that Barbour had ever heard anything other than equal temperament when he wrote the book, as he once admitted.
Ross W. Duffin, How Equal Temperament Ruined Harmony
Duffin calls tuning “that pesky problem of dividing the octave into 12 notes.
As evidence of Barbour’s never having actually listened to music in the tunings he wrote about, Duffin cites a 1948 letter by Barbour to A. R. McClure, via Mark Lindley.
(To hear an alternative tuning system, try for example La Monte Young’s Well-Tuned Piano—nice for long car trips.)