If you love jazz, there are going to be no fewer than a hundred "must have" jazz LPs. Ditto for classical. The "sub-question" of what LPs do you play to show off your system raises the question: Do music lovers value sonics over great music and great performances? Unquestionably, great sonics enhance the experience. You cannot even hear Charlie Parker's gorgeous sound until he was recorded in 1952 in hi-fi by Norman Granz (listen to his interpretation Dearly Beloved on this "must-own" Norman Granz Jam Session/The Charlie Parker Sides). But there are many pre-hifidelity recordings that are far more aesthetically and emotionally involving than their modern counterparts. For instance, For Duke recorded direct to disc by Bill Berry and his Ellington All-Stars will show off your system, but I would rather listen to The Early Duke Ellington(or any Ellington recording) transcribed by Everest Records from 78s recorded in 1927. You've got the master conducting and at the piano. It's not a "must own", but it's the real deal.
I have found that at a gathering of audiophiles, there is a certain pressure to play sonically impressive recordings. But if you are playing records for musicians, it is all about the music. We know about ear fatigue when our systems are not set up properly. We have to become acquainted with another kind of fatigue when the music isn't deeply engaging. That involves listening to music that may at first not be easy to appreciate, but which, once assimilated, you cannot live without.
I have found that at a gathering of audiophiles, there is a certain pressure to play sonically impressive recordings. But if you are playing records for musicians, it is all about the music. We know about ear fatigue when our systems are not set up properly. We have to become acquainted with another kind of fatigue when the music isn't deeply engaging. That involves listening to music that may at first not be easy to appreciate, but which, once assimilated, you cannot live without.