The current offerings of both types, and moving iron too, are such that it becomes more a matter of personal choice, taste and system compatibility, not necessarily in that order of priority.
So that wasn't very helpful was it?
About 12 years ago I switched from a nice Grado moving iron to a Benz Micro MC and immediately enjoyed what I perceived to be added "air" and inner detail that I felt, at the time, was afforded by the MC design. Since then I have stayed with MC by default, but a few friend's systems that use MM or MI and that I get to listen to regularly are also highly enjoyable.
An important part of this is consideration for the phono pre and other downstream components that will be used. After all, we listen to systems, not cartridges in isolation.
So that wasn't very helpful was it?
About 12 years ago I switched from a nice Grado moving iron to a Benz Micro MC and immediately enjoyed what I perceived to be added "air" and inner detail that I felt, at the time, was afforded by the MC design. Since then I have stayed with MC by default, but a few friend's systems that use MM or MI and that I get to listen to regularly are also highly enjoyable.
An important part of this is consideration for the phono pre and other downstream components that will be used. After all, we listen to systems, not cartridges in isolation.