16 has the highest resolution in XF. It resolves more details if you zoom in to 100%+. And F/1.4 makes it such a wonderful lens for galaxy photography.
But if I had to choose, I'd still go for 10-24 and 35 combo.
There're 2 reasons that the advantage of 16 can't really attract me.
1. I don't take landscape for commercial purpose. The super high resolution isn't a MUST.
2. Of course I don't always take galaxy that often.
And here is the reason why 10-24 can be the replacement.
1. Landscape seldom taken by big aperture, F/4 is huge enough, except galaxy.
2. 10-24 gives you much more than just 16.
----24: A 36mm in 135 is wonderful for street photography.
----18: A 28mm in 135 is another nice option for street photography and it's also suitable for landscape.
----16: A 24mm in 135 is just nice for usual landscape.
----10-14: Ultra wide angle provides a strong visual impact to your photo.
Ultra wide is not a MUST, but you'll falling love with it if you have one.
I do use 14 to take portraits. The perspective makes girls leg longer and thinner. And the visual impact with good background such as great architecture gives you a stately feeling.
3. Every time before travelling, I never think about which lens to bring. I just mount my 10-24 onto the camera, that's all I need. No matter street, cityscape or great landscape, the 10-24 can manage everything.