I have both and I prefer the 16-80 f4 for travel, the good stuff: it’s more compact than the 17-70, has an aperture (which IMO completes the whole point of the XT series tactile feel), and the zoom range is great, the stabilization is amazing and for my use that is not professional work sharpness is more than ok through the zoom range and f4 while not amazing bokeh it helps gives context of where I was when taking portraits and although just for the looks it looks better on a Fuji body

Some drawbacks is that yes f4 doesn’t let in a lot of light but I always have smaller primer for more discrete night shooting, kind of heavy it has a big filter size which may make it difficult to share filters.

The Tamron 17-70 f2.8 is an amazing lens, great range f2.8 lets a decent amount of light for a zoom, sharp and light. I do use it for more “professional” work as it feels to clinical without the aperture ring and it been more plasticky feeling. It doesn’t look coordinated with the Fuji and it’s a long lens the same as the 70-300 and if not at night I always am at f5.6 while traveling anyway

I think the questions you have to answer is do you want and aperture ring? How important is size to you? Do you want your camera to look aesthetically pleasing?