An interesting experiment, Gianluca.
The first and the last work well for me although my own taste is for blacker black and whiter whites.
Converting a colour image to monochrome in post works well for the right subjects. It's something I often do with digital to save faffing around changing the camera's settings. And, more importantly, remembering to change them back again!
I'll post one that I took the other day before we actually started the canal walk. It works much better in monochrome I think.