While it may be the best, the SAS is a dumpster fire on the V15V, IMO.
For the SAS on V15V bodies - you say my postings of custom loadings - it requires custom loading to get close to its potential
Without that custom loading .... you might as well be randomly fiddling with a 5 channel equaliser
For the most part MCs are anything but flat. Even Technics with the 305MCMK2 that came out at the same time as the 100CMK4 isn’t there. Sure, they exist, but few and far between IME.
I was being diplomatic....
I would refer you to the Dynavector Ruby/Karat series - I have one, it is quite remarkable
I know some people will find the next paragraph difficult but:
Once we accept that cartridge loading is mostly cartridge EQ - and we therefore accept that EQ is a fundamental and necessary part of optimising a vinyl setup - then we can get progress.... and that means an optimised phono stage ADC - possibly with some EQ before the ADC to move the dynamic range which varies by frequency, into an optimal frequency spectrum for digitisation - followed by a fully digital EQ stage that applies both RIAA and cartridge EQ - same as we do for speakers...
Once you have taken these steps - all you need from the cartridge and stylus is a good reading of the walls of the track - with minimisation of added artifacts (tonearm/compliance resonance, cantilever mass resonance, cartridge generator eddy currents, etc...) - flatness of frequency response becomes a non-issue - you want sufficient signal to be able to work with it - you don't want your signal to be more than say 15db +/- from your reference 1khz tone (as that makes ADC & EQ dynamic range more complicated) - and you then EQ the same way you would with a speaker (which is the other component that cartridges most resemble technically)
So for my ideal generator - I would pick a cartridge body with relatively low mass (not too heavy) - good ease of mounting - and as many laminations as possible of the MM generator core (to minimise eddy currents).
Shure V15V is good (so is the V15IV, and the p-mount V15 variants) - laminated core.
The AT upper models AT150, AT15/20 are excellent, also laminated cores - but getting good styli for them can be variable (Jico is clearly in some sort of non-competition agreement with AT!)
Some of the other classic cartridges are in this category too - eg: JVC Z series (for which SAS is available!), with some of the other vintage brands that are long out of production, it is hard to find out details of their design / manufacture - such as whether the core was laminated - so even if great styli are available - it is hard to tell whether they are top grade contenders.
I have also found some variability in SAS styli - with one stylus having a resonance around 14kHz and another around 16kHz - in theory a high quality exotic should have its resonance above 20kHz (preferably above 30kHz) - I believe that resonance to be not the primary cantilever resonance, but something relating to the tension wire & suspension at the rear... but that is pure guesswork.
Or, bite the bullet, and get a truly great design from the golden age, that is still in production today - the B&O MMC Series... now known as the SMMC series from Soundsmith.... (and their various "audiophile" upmarket blinged up versions) - at a price
.
P.S. when I jumped aboard the SAS bandwagon, I was picking them up at around US$160 - they are now twice that price.... so where I originally "pushed" them as a fantastic value top performance stylus (for those willing to do the work in EQ) - they are now decent value - but not stunning the way they were 10 years ago.