What is they best album out there for showing off the sound quality of your system.

An awful lot of great sounding music mentioned here but I agree with @tomcarr, let your friends and  guests pick. Otherwise you’re just looking like the arrogant dork audiophile that you probably really are at the core.   Sure, it can be a solitary pursuit, but try not to be so self centered.  Really.  
I mean, if you have a truly good sounding stereo it will hold up (or perform maybe even exceptionally well) on their favorite.  

473 posts11-30-2019 6:23pmAlbum is called Hope, by Hugh Masekela
but the cd , or SACD if you can find it.
spark one , light a few candles and enjoy this incredible album!!!!!!!
listen to the entire album all the way through .
its a religious experience.
here is a taste:

https://youtu.be/n4Bb7p9gggc

Thanks toddnkaya   very much...………..This album do what you say it must do....

I’m surprised not one has mentioned any of the Tonian Trio recordings (Moon Jazz would be my pick).
While not the most melodic jazz, the sound quality is pretty amazing and shows that high-res digital files have nothing over a properly recorded and engineered redbook CD.
Also including Ron Carter and Jim Hall’s double album "Telepathy".

The first Black Sabbath album 

+++ Black Sabbath - Black Sabbath - Black Sabbath

What happened after Paranoid?