let me add some to the above. The LO output carts (MCs), as Raul pointed out have a lesser internal resistance due to fewer windings --- BUT fewer windings in an MC ALSO means less coil weight to slug about (less inertia). Both will, all things being equal, result in higher signal resolution. This has per se NOTHING directly to do with TONALITY, which you might like or not, given any particular cart.
The theme goes further. As the 'old school' of course has a point also: higher output is ALSO better for reasons Raul mentioned, --- BUT NOT AT the expense of more coil weight!
A HI output MC will always be more resolution/detail challanged than a LO output one.
So whats left now is the magnet and flux plate. A more powerful magnetic field, AND better magnetic flux can now create MC carts with as little as 1.5 ohm internal resistance (very light coil with fewer windings) AND close to 0.6 mV output. So far the best of the two worlds. 'Transfiguration' and 'Airtight' offer these ---- BUT you have to pay for it ~ 6k$ to ~8k$ respectively.
If that is too much $$$, then I would still go for LO internal resistance with a low mV output as a trade-off ----- provided you consider a phono-pre that has a trannie OR using an external step-up trannie.
With the low output cart the trannie will pull maximum current from the MC and comfortably convert it into the desired higher voltage of 5 - 8mV with no added noise(higher ratio would produce distortion in the phono-pre).
This method is still best to avoid tube noise, or even solid-state noise ---- BUT it also improves the MC cart's performance noticably in overall dynamics and bass.