What is the VERY BEST CD album you've ever heard?

Spyboy, Emmy Lou Harris. You're there. Hard to find, out of print before the vinyl resurgence. 

@8th-note I was happy to have seen Col. Bruce and ARU a few times. He might have been a strange character but the music was impeccable. I am basically frightened - by how good it was.

@czarivey Guess Coldplay is pop too then. Maybe even Metallica.

I really can’t answer the OP’s question. Choosing ONE CD as the "best" is nearly impossible. Maybe one by ELP or YES - but which one? Then you have crazy classical pieces that are staggering. Singer songwriters with good playing and great vocals. Molly Tuttle of late, etc.

Ah, so many CDs (or vinyl) and so little time...

Any SACD on a PS Audio SACD player. And standard CDs shine brighter as well. Agree with the above regarding Live at Fillmore East, and Take Five.

For the category of great live CD performance and mediocre recording quality, I would nominate Delaney & Bonnie & Friends On Tour, With Eric Clapton.

all-right.

Let's call the common stuff mainstream whether it's rock or pop or hop of any kind.

Mainstream usually can be found in thrift stores for less than a buck

Blood Sweat and Tears, Original Master Recording. 24 kt Gold Plated.