Best Album Purchase, or Best Evaluating Record


I would just like to know what you consider your best album purchase ever, or your choice of album used to evaluate a stereo system.

My best purchase has to be about 300 - 400 classical records, for $300, that contained many mint shaded dogs, Living Presence, and blue Backs (among others).
licoricepizza
For evaluation I like:
Come Away With Me- Norah Jones
Time Out- Dave Brubeck Quartet
I have the David and David record too, and it is good for a lot of reasons. The lamest purchase I ever made was a Jay Ferguson cutout, back in my college days. At least it has Thunder Island on it!

I also have the Norah Jones, and the Dave Brubeck albums. Not only is the Brubeck a mono copy, but it looks like the previous owner used it for a Frisbee in the street.
The best ablum you could use in evaluating a system is the one that best represents what you like to listen to. If it sounds good that would be an indicator that you're on the right track.
Miles Blue. I own this music in five different media types, played on ss and tube rigs. The vinyl is still the best and when I go to dealers to check out new speakers, I use that as a reference. I take both the vinyl and sacd. A blu-ray will be available shortly. Wow.
I bought Rickie Lee Jones' debut album when it first hit the racks in Tower Records on the Sunset Strip in 1979. I think I paid $4.99 for it. Great recording, fine stamping, and still one of my reference LPs after all these years.