OP, great idea for a thread!
This is obviously a very subjective thing, right? It has a lot to do with our individual preferences and taste.
Joni Mitchell's song A Case of You is such a gorgeous song, imo. But the first time I ever heard it sung by her I was like, Ew! lol
I had been listening to it for years, as sung and performed by Diana Krall ... and then one day it came up on Radio Paradise in the middle of an afternoon at my office performed by Joni Mitchell. I could hardly believe how turned off I was by it. And I'm a pretty big Joni Mitchell fan. I've been listening to Ladies of the Canyon since I was a teenager and have enjoyed a lot of her music. But listening to her perform that particular song, for me personally, is kinda like finger nails on a chalkboard.