As I remember, the M2 was briefly made by Leitz as a budget model. Because fewer made than other Ms, collectors interest reason for high prices. For same money possible to buy user M3 or M4. Other cameras also fetch high prices due to scarcity rather than quality. This does not mean that the M2 is a bad camera...in fact I had friends who preferred it over the other M cameras.
Of course, there can be no argument for personal preference. As a perusal of apug reveals, there is no “best” camera.