The black paint Leicas M2, M3, M4 from 1967 to 1971 and new MP are very beautifully finished but, also, are very prone to scratches.
The black chrome Leicas M5, M4 from 1974 to 1975, M4-2, M4-P, all M6 versions and M7 are less fascinating in the finishing, but are very resistant. I prefer this second solution.
Ciao.
Vincenzo