MC cartridges are generally considered the better sounding option because of their lower moving mass. They are better at picking up details in the record grooves and can therefore reproduce the fine details in the music with higher accuracy than MM cartridges. The differences between MM and MC are more apparent when listening to very high quality recordings on a high-end turntable, a good quality MC cartridge like Hana ML will produce more precise soundstage and finer details than a similarly price MM cartridge.
This is not to say that MM cart can’t sound good. It is my opinion and understanding that MM cartridges with their higher moving mass, have a tendency to “smooth out” the fine details. For affordable low-end turntables, MM cart is the most obvious choice :-)
And then there is difference of signal output levels. The typical signal output from a MM cartridge is 5mV. While a MC cartridge typically outputs 0.2mV.