Good handling is always a big advantage for any gear combination. Mainly due to the lack of a view finder, I find myself using the Z30 mainly with wide or very wide angle lenses. On the Z fc these would mainly be Viltrox 13mm or 23mm, both f/1.4 designs, but they don't work well on the Z30. Again handling is the biggest issue. The lack of a viewfinder throws a spanner in the workings of the ultrawide Laowas like 9mm f/5.6 or 11mm f/4.5, as contrary to common myths about the large depth-of-field of wide lenses, they both need critical focusing to deliver their best. And a rear display in sunshine isn't the preferred approach to put it mildly.
The Voigt 15mm f/4.5 is just about perfect on the Z30 -- for me. Easy to do zone focusing by the handy focusing lever which is click-stopped at 1 and 0.5m setting; perfect for discreet shooting. One gets the feeling for the coverage and if doubt a quick look through the optical finder will help. The lens also adds some heft to the camera thus improves hand-holding it.
The kit lens 16-50 is optically speaking quite good, but hardly looks like it can take a beating in the field. I use it occasionally when nothing special is on my my mind.
