List of artists that have never lost quality throughout entire career


One of the brightest on my list is 

1. Depeche Mode. I'm big fan started listening and enjoying them from their very first album "Speak and Spell". I am devoted to their perfection of every song they create in terms of sound, melody, harmony and incredible intelligence. Their music may seem simple, but in reality much more complex than seems. I believe that they're somewhat commercialized, but also believe that they deserve their incredible success. They're indeed Kings of electronic rock!

2. Can (The Can). Every album they released is a journey to their creativity. What are they rock? Jazz? Prog? Their music often can cover all styles of music in one song. It's a blend of jazz-trained drummer Jaki Libezeit, classically trained keyboardist Irmin Schmidt(also conductor and neo-classical composer and film score composer), multi-instrumentalist bassist Holger Czukai and classically trained guitarist and electric violinist Michael Caroli (RIP). It's a unique blend of musicians with extraordinary skills and creativity

3. Dead Can Dance. This artist has plenty of praises and each and every of their album is a unique blend of electronics and earth bound instruments. Lisa Gerrard is known to be a part of Gladiator Motion Picture Soundtrack.

4. Tom Waits. Many would criticize Tom for not singing his own voice, but I'm amused the way he does it with spirit of Louis Armstrong! Yes indeed with spirit instead of just imitating. Embracing the spirit of inspired artist is different and Tom is clear example to that!
czarivey
@dekay 

Haven't thought of George Gobel in decades but when you mentioned him, this quote came to mind:

"Did you ever get the feeling that the world is a tuxedo and you're a pair of brown shoes?"

Yes. I have. 
Bruce Springsteen is an artist whoose work has matured and grown.  lyrically  he's become more complex as well.   I heard some of his recent shows where's he's performed Born in the USA and The River.   I not only saw this music performed in the era of its release, but have recently heard recordings of these old shows. 
His band's  new performance of this old material show an incredible musical advancement over the old shows.   The arrangements are similar but are so much more masterful. 
Excellent call on Van Morrison.

I’d include Andy Summers (especially, post-Police) and Neil Finn/Crowded House.