Many artists have "arcs" in the quality of the work. Up, then down, hopefully then up again. There is the thought that most have only "so much" in them, some only one album. What a depressing idea for those just beginning. I can think of many bands or singer/songwriters who apparently shot their wad with their first release. Many of my long-term favorites---Ray Davies/The Kinks, The Beatles, The Band, The Dwight Twilley Band (with Phil Seymour), only two or three. I’m in the minority, but only Rubber Soul and Revolver make the grade for me! Some only one---Rockpile, though they did a few more as an ensemble on Dave Edmunds and Nick Lowes solo albums.
It’s the writers I find of interest for the longest stretches---currently Iris Dement, Rodney Crowell, John Hiatt, Loudon Wainwright, Jim Lauderdale, maybe Lucinda Williams (she does too many slow songs), Marshall Crenshaw. Dylan, of course. Performers are Buddy Miller, Emmylou Harris, Alison Krauss, Patty Loveless, The Del McCoury Band, anything by Marty Stuart or Chris Hillman. Hmm, all Country--ish.
The saddest for me are those who stay past their prime---particularly Brian Wilson. Seeing him live in the early 2000’s was about as depressing a thing as I’ve ever experienced. I was morose for days afterwards. Then there are those who finish strong. Johnny Cash!