As for my opinion on this subject, the differences between most well made cartridges are relative to the flowery descriptions I see, minor.
The most obvious is output and dynamic range. Next is tonal balance. Some cartridges lean a little bright others a little bass heavy. Ralph is right. As long as a cartridge is tracking everything you throw at it, any preference is personal. MC cartridges in particular are vastly over priced and many do not represent a good value. Take a look at the Nagaoka MP500. Here is a cartridge for $800.00 with a fine line stylus, a boron cantilever and great reviews. I would bet it is a better rock and roll cartridge than most MCs. Soundsmith and Grado both make excellent reasonably price cartridges. The Kiseki Purple Heart is just as good as cartridges costing $10K Price is absolutely no indication of quality when it comes down to MC cartridges once you get to a certain level of quality. The Ortofon Quintet Black S, the Clearaudio Essence and the Van Den Hull DDT-2 are excellent examples of cartridges using the best modern tech and materials at reasonable prices. After this it becomes purely a matter of taste, ego and tonearms. We have some fabulous tonearms on the market now but that is another subject.