I have all sorts of lenses and many different subjects. I have only shot one lens on my Fuji though, and I only really need the one because I know it is by default going to be the best! The Fujifilm XF 16-55mm f/2.8 R LM WR (absurdly long name) is my go to lens for all things landscape now and for many good reasons.
When choosing a lens for landscape photography most will default to whatever is widest. Having used everything from wide to telephoto though I can tell you with certainty the extremes are not the way to go in this genre. If I only have one lens to shoot with I would want something that goes from fairly wide to fairly telephoto because that is going to cover far more situations photographically.
The best compositions tend to be somewhere towards the middle focal lengths. Whereas if you have a wide or telephoto lens you have to shoot at the extremes (16mm on a 16-35 and 200mm on a 70-200 full frame). The 16-55mm on the Fuji has an equivalent full frame range of 24-82.5mm which allows you to do a lot more compositionally shooting wide, telephoto, and normal focal lengths whichever pleases you and the scene best!
It has to be a zoom lens in landscape photography. The versatility and flexibility in the field is unmatched by any collection of primes. The weight also is down compared to having 2-3 lenses that kind-of line up with the 16-55mm you have only the one set of elements to tote around. Also, there are a lot of conditions you will find yourself in where it is not a good idea to be swapping lenses on the camera body!
This lens is superb. There is no other word for it optically as it is masterfully done. Corner sharpness is on par with my Nikon 16-35mm on a D800 shot at 24mm vs the 16mm on the Fuji which is saying a lot because that is the middle of the zoom range on the Nikon compared to the edge of it on the Fuji. The sharpness only gets better from there! It is also an f/2.8 allowing a large amount of light through for extreme low light and astro. Zero complaints!
This is one area I have yet to fully test, but I have had it out in a couple situations where it performed admirably. I have shot in the rain without cover and the lens did not malfunction, but I do have some concern about moisture and dust creeping in via the zoom mechanism because the lens does not zoom internally like my Tamron 70-200mm does. I have also had the lens in extreme cold where I was able to easily operate its zoom with gloves on and it braved the extreme temps well (up on Mt Hood in the winter).
So, this might be more of an opinion piece about how I think this is the best lens for the job. The job being landscape photography with a Fuji camera system. However, I do have some experience in the subject matter and I have a lot of confidence, stating it as a fact that the Fujinon 16mm-55mm… so on and so forth: is the best Fuji lens for landscape photography. If I could only have one lens, it would be this one!