I haven't read every post in this thread, but I'd like to add my own perspective to the issue. First, their is no "best" cartridge. Only one that keeps you satisfied with the music you listen to, and as long as you can keep the "time to upgrade" demon in check. But that still doesn't address the "how can I chose" issue.
That "how can I chose" issue has been with us forever, even in the seventies. It is one of the reasons Harry Pearson's The Abso!ute Sound magazine took off like a missile ..... Harry had been an environmental reporter, attuned to the real word and balanced reporting. Harry also had a superb ear, the ability to describe what he heard in words with a developed (with Gordon Holt) vocabulary, and access within a few years to virtually every cartridge then on the market. When you decided to buy a cartridge that Harry had reviewed, you still might not like it, but at least you had an idea beforehand as to "what sound" you were buying. You also got a lot of information to help that choice ..... tone arm mass reommendations, VTA recomendations, etc. There were several reasons why this worked. Initially Harry's credibility was raised because he accepted no advertising, and even when this policy changed later, for a period he would only accept dealer (not manufacturer or distributor) advertising. Secondly, he developed a cadre of also-respected reviewers and included second and third opinions on all the stuff Harry really liked (or disliked) as a reality check. And finally, the magazine included a lot of listener feedback, which often was more in support of the assessments Harry made (after laying out their own money) than in opposition.
Now Harry was without his flaws, and he was probably the originator of Audio's "if its more expensive, it most likely is better" mentality once he heard the Koetsu (which he did not describe as accurate, but did fall in love with it's strengths.) The problem with this: by the time the next "great cartridge" arrived, the original had been shipped off to other reviewers for commentary, and sometimes back to the distributor from which it came. So he did not do many direct comparisons, and after awhile fell into the trap of believing he could remember accurately enough to declare "this one better than that (past) cartridge, in this or that respect." Such might or might not have been true, but over time it was likely if the new cartridge was more expensive, or more exotic, it was given the benefit of the doubt.
Initially, Harry and I did share a belief (which I was why I came to play a minor role in the first eight issues) that comparatives could only take you so far and that attending live musical events (lots of them) was the only thing that could attune you to what was present or not present in the cartridge or other component under review. In addition, of course, to only changing one thing at a time.
In my case, back around 1980, when I switched into moving coils I managed to listen to the Dynavector Ruby and the Accuphase AC-2, both of which had been judged neutral-sounding but "musical" by TAS, and finally purchased the AC-2. Two years later I bought two more (used) as backups as audiophiles abandoned them to follow Harry's "latest and greatest and more expensive" cartridges. I knew I would never upgrade my cartridge further, and never have.
Two incidentals: in today's dollars the AC-2 would fall around $1800 and the Dynavector Ruby a bit over $2000. So you might want to consider $2000 as a reasonable benchmark for getting a top-flight MC cartridge. And secondly, I still go to dozens of jazz and chamber and orchestral concerts a year. I often listen with my eyes closed, as I do when listening to my system at home. I get the same listening satisfaction from both. I'm not sure a cartridge can deliver more than that.
