With the recent introduction of the Tamron 17-70mm F2.8 Di III-A VC RXD for Fujifilm X Mount, the fast standard zoom options for the X mount increased to 4 lenses: Tamron 17-70 F2.8 Di III-A VC RXD, Fujifilm XF 16-55mm F2.8 R LM WR, Fujifilm XF 16-80mm F4 R OIS WR and Fujifilm XF 18-55mm F2.8-4 R LM OIS.
Here we have a scaled size comparison of these 4 lenses followed by a specs comparison to give you a better idea about what the new Tamron lens offers: (click on the image for larger version)
As seen on the image, Tamron is the tallest of the four but considering it is a constant F2.8 aperture and have a wide zoom range compared to all but 16-80mm, it is hard to blame the new lens. It is also lighter than the 16-55 F2.8 lens. One other advantage of the Tamron 17-70mm is that it is an internal zoom lens so don't change lenght when zooming, helps in case of gimbal stabilizer use.
Specs and Feature Comparison