Besides Aja and zeppelin pressings, what others are demo level recordings?

It is not the pressing that is important although quiet is always better but the quality or the recording and mastering which for most popular music generally sucks. Being able to blow someones doors off may be fun but it is not the hallmark of the best systems. With the exception of Waiting for Columbus all of my pet demo records are either Jazz or classical.

Any Analog Productions album. Janis Ian's Breaking Silence is a nice start. It is hard to believe how good the Buddy Holly recordings are. These are handily the best quality vinyl made in the States. Substantially better than regular Mobile Fidelity discs and easily the match for their UltraDisc pressings. wakethetown is very right with Dreams and Daggers.
Cecile Mclorin Salvant may be the modern Ella. Her control is that good. I have the high def version so I can speak for the vinyl but buy it anyway. There is no modern jazz vocalist that is this good and I am including Cassandra Wilson in that comparison. 

millercarbon I do not know about you but I have no problem listening through a rather crude pressing to the quality of the recording, engineering and mastering. It would be nice if all records could be Analog productions pressing but that is not life. One of the best recordings I have ever heard an early McCoy Tyner disc called Asante came during the period that Blue Note pressings were typical American crappy. I love that record. The music is incredible along with a fine engineering job. Hopefully one day they will release his catalog in high def but for now this is what I have. Modern engineers seem to want everything in your face.
You have the sax on the right, bass in the middle, Piano which goes from the left all the way past the sax with the high hat in front on the sax and the bass tom in front of the piano all the way on the left. I have yet to see a drummer with 12 foot arm and a piano keyboard that is 20 feet wide. Unless you are modern King Crimson drummers are usually in the rear. This is the stuff that drives me crazy. A lot of it may be do to the monitors they are listening to. Whatever, they actually engineer the reality out of the recording. I want to able to close my eyes and hear the band in front of instruments located and sized correctly. Asante does this beautifully. I'll live with a few pops and clicks.