What artists can you not get enough of?

From the question I assume you mean the ones I spin the most, so these are my current top 20:

1. Boz Scaggs
2. Elvis Costello
3. Burt Bacharach
4. Burt Bacharach and Daniel Tashian - Blue Umbrella Recordings
5. Chet Baker
6. Bill Evans
7. Pat Metheny & Lyle Mays
8. The Allman Brothers
9. Michael McDonald (with & without the Doobie Bros)
10. Pink Floyd
11. Jackson Browne
12. Jimi Hendrix
13. Beck
14. Paul Simon
15. Tears for Fears
16. Yes
17. Shostakovich
18. Mahler 
19. Ralph Vaughan-Williams
20. Mozart 

As one of my best friends says 'too much music, too little time' and for my extra picks Nick Drake, Jeff Beck, John Coltrane, Stan Getz,  John Martyn and many more......

The avatar says it all.

I’ll rephrase the original question slightly. The artists I can listen to their whole catalog, and listen to day after day. (also based on what is in my library):

Talking Heads

The Byrds

J.S. Bach

Next tier: (may need a break between - not quite day after day)

Dire Strits

Pat Metheny

Leo Kottke

Ry Cooder

Nitty Gritty Dirt Band

Merle Haggard, Bob Dylan, John Prine, John Lennon, George Harrison

Liz Wright

Leonard Cohen

John Prine

Mark Knopfler

Tony Joe White

Dean Martin

Willie Nelson

k d lang

Ruthie Foster