What is the “World’s Best Cartridge”?

Didn’t realize Koetsu’s went up to 20k. A quick Google search found this.  

@rsf507  That's with the diamond cantilever +$5K add-on option. That pink Rhodenite stone is also now discontinued, along with Coralstone (ran out of material). The standard boron models still top out at 15K or 16K (for Blue Lace), which they have been at for many years now.

Anyways, the large premium on certain stones seems to be thanks to the regional distributors more than  Koetsu Japan. And a more "pedestrian" RSP or Onyx with boron cantilever still sounds exceptionally good and embodies the full Koetsu sound (for that matter the Urushis probably do too - I want to try one). They all have the same motors inside.

@mijostyn 

The MSL's super-high ratio of output voltage to coil impedance seems to be unlike anything else out there. In fact there's nothing even close (besides Air Tight). Definitely intriguing - must be some super efficient combination of armature and magnet structure? 

The low 15kHz channel separation spec on Ortofon's MC Diamond is interesting - and it's not just the Anna that they've spec'd higher. 20dB is not impressive. Even much lower line cartridges like Kontrapunkts have been spec'd higher! Probably some of the vintage models too. Possibly an admission that measurements take a backseat to subjective sound quality?

"Even much lower line cartridges like Kontrapunkts..."

Careful, lad, I’m listening to a 500 hour Kontrapunkt C and thinking it is uncomfortably close to what I like about the London Decca Reference. That alone makes me think Ortofon have some idea of what they are about. Unlike some cartridge manufacturers. The Kontrapunkt C is akin to the Cadenza Black in modern speak.

I actually owned a Kontrapunkt c, and am sorry I sold it. Loved that cartridge. It’s analogous to Cadenza Bronze in the modern line - which I also have - and in many ways I think the Kontra c was more fun (though they’re a lot alike). Even preferred the "c" over its big brother Jubilee, which was predecessor to the Cadenza Black. The Jubilee was a bit sterile. The Kontra c and Bronze have a warmth and body that seems to be missing to various degrees from the upper line (Jubilee, Windfeld, Windfeld Ti). A90 is my favorite Ortofon so far, though.

My encounters and following assessments lead myself to a different approach of thought, I am convinced the K’b is a not too attractive Cart’ when used on certain Designs for a Tonearms and can be underwhelming, even though replaying the music in a manner that can be enjoyed. The K’b is a Jekyll and Hide, as when used on another Design of Tonearm, the Design is quite capable of excelling, and becoming very attractive in use. When partnered with a Tonearm of a certain design, the K’b has proven itself to compare very favourably to much more expensive Brand family members, leaving not too much amiss in the comparative performances.

Having about a dozen upper-line MC’s I rotate among, I can for sure say that some are particularly hot or cold (or chameleon-like, or Jekyll & Hyde, etc) depending on what gear they’re mated to. But here turntable and speakers remain constant; even the tonearm is usually constant now as I’ve settled on the 2nd FR64fx as my "sandbox" arm. But some cartridges have been particularly sensitive to SUT pairing first, and then preamp & amplifier second. Even tube rolling selections can affect this:

• Shelter Harmony - When Cold: A bit too hot up top, and too lean in the midrange through upper bass. When Hot: Amazing clarity through midrange, fast, tight & punchy bass, sparkling highs and beautiful staging. Can pull new life out of some pressings on the dull / dark side.
• Ortofon Windfeld Ti (and MC): Cold: Dry and boring overall. No life in the midrange. Sounds like good (not great) digital. The older MC version had these problems plus too hot treble. Hot: Well balanced, super clean linear & neutral. Very fast response! Spectacular quality treble, like a top flight Stax headphone system, without being too overblown. The opposite of being lifeless; it brings life to the music. Ti is cleaner, smoother than MC. The Jubilee is similar to Windfeld MC too, but not as good and I never got it to work for me before trading (it worked well for the friend I traded it to).
• Benz Ebony L: Cold: A little anemic (or at least reticent) in bass. Sounds like a slightly atrophied Koetsu. Perhaps a touch hot on top at times. Hot: Beautifully musically balanced while showing far more refinement than lower Benz models; a near flawless manifestation of the classic Benz iron cross sound (IMO), and a good affordable alternative to Koetsu.

Then there are cartridges which seem quite happily situated in MOST system configurations I’ve tried them in. Of course proper matching can still take them further, but you’re less likely to have a disappointment here. To me, these include:
Koetsu (all), Shelter Accord (far more easygoing and affable than its big brother Harmony), Ortofon A90, Kontrapunkt "C" and Cadenza Bronze, Benz Zebrawood.

There are endless variables to cartridge use cases, and endless variability in user preferences, which is why these discussions are similarly endless...

Sadly, cartridges are too easily damaged, which makes rentals a tricky proposition. I mean, we still see the "my cleaning lady killed a $5K Dynavector" posts every month - too many audiophiles still haven't got their "cartridge safety" routines down pat. You could charge the renter for damage, but that will lead to a lot of "you damaged this cart" / "no I didn't - CC chargeback incoming" quagmires.

You might discover that you can not hear the difference between a Windfeld Ti and an MC Diamond in your system. That is a $5000 savings. 

I agree with the point you're making, but the differences between cartridges of different designs like that are extremely audible. Nobody who can't hear that difference will get to the point of interest in $5K+ cartridges. However, it IS possible they might prefer the cheaper cartridge, due to either system matching or personal preference.