My first M camera was the M2, which I still have. My second was a beautiful M3 but since it didn't work with the standard 35mm lens I sold it and bought a brand new M4-P which I still have.
The finder in the M3 was not that much better for me than the finder in the M2 so I had no compunction in letting go the M3.
I like the simplicity of the M2 even compared to the simplicity of the M4-P. To solve the glasses issue I found proper -2 diopters that screw into the finder that allow me to remove my glasses and see the whole frame in both cameras.
If I were obliged for some reason to need to replace my M cameras I would get another M2 without hesitation. Then perhaps a M6 to replace the M4-P.
I have always thought the M2 was a nicer camera than the M3. Sleeker and more efficient with the better (for me) framelines. It is just as slick to use as an M3 and importantly it is an easier camera to buy in good condition because they tend to be newer and without the M3 premium.