There are so many to choose from, but I think any list has to include:
1. Doobie Brothers - before, during, and after the Michael McDonald era.
2. The Eagles - every single member of the band is a standout and what a library of work.
3. Fleetwood Mac - talented musicians and singers - Stevie Nicks, Lindsay Buckingham, et al
4. Steely Dan
5. Buffalo Springfield (and all of its succeeding subgroups)
6. ZZ Top - Great mix of hard rock and roll with a little Country thrown in for good luck
7. Credence Clearwater Revival / John Fogerty - nothing quite like it and never will be
8. Greatful Dead - not big on recorded music, but their concerts were always unmatched events
9. Aerosmith - Steve Tyler was lead, but everyone in the band was a star.
10.Beach Boys - All-American. Good music, great writing, harmony, rock, soft, surf - they covered it all.