Hi Jacek,
at first sight I thougt XC16-50 OIS II is wonderful! It is a light weight and as such in the city e.g. I have been happy about.
I did not do any pixel peeping, but please have a look at this:
There is fringing between the horizon and the woods, the woods at larger distance themselves are somewhat „muddy“ with the XC16-50mm OIS II.
When having a look at the following picture taken with the XF18-55mm at another location you will clearly see what I mean: the picture hase more depth, a better solution and the green colors are natural and differentiated.
You may decide by yourself – I decided in favour of the XF18-55. In my appropriate city bag it is not too heavy for walking around...
Kind regards Rieke