My most played 45's are all jazz. My favorite is "Bill Evans at the Montreux Jazz Festival" (Classic Records).
A close second is "Cool Struttin" with Sonny Clark, Art Farmer, Jackie McLean Paul Chambers and "Philly" Joe Jones (Classic Records).
The one I originally dismissed, "Time Out," The Dave Brubeck Quartet, turned out to be a real surprise. I have so many copies of this jazz masterpiece I originally dismissed the possibility of yet another copy.
The first time I heard this was my original 6 eye, purchased in college and still sounding great after all these years. Since then I purchased two additional Columbia reissues, along with the (excellent) 33 RPM Classic Records version.
Believing I had memorized every note and nuance of sound from the shear number of times it spun in my system, I was not expecting anything new from the 45 release. Surprisingly, this version revealed the session in ways I never imagined. Not just more energy which is the hallmark of 45 RPM's higher velocity, it is more "there," in a musical sense, putting you closer to the musicians instead of just listening to them.
Small details, as well as the drums, have texture combined with impact that is lacking in every other pressing. A long time annoyance that I thought to be in the original tape, was the quality of the cymbals. Now they have the natural metallic sheen that has been absence in every other pressing I own and have heard.
I believe these are worth the investment, not only from technical excellence, but for their ability to make the music more enjoyable.