Depends on your budget and specific needs! If you're doing astrophotography, I'd recommend either the Z 14-24mm f/2.8 S (amazing sharpness across the frame, perfect for wide star fields) or the Z 24-70mm f/2.8 S if you want more versatility for different night subjects. Both are pricey but worth it. For a budget option, consider the Z 24-50mm f/4-6.3 - not as fast but still capable, especially with the excellent high-ISO performance of Z cameras.

For night photography, you can't go wrong with the Nikon Z 20mm f/1.8 S. It's incredibly sharp wide open, has minimal coma (crucial for astrophotography), and the f/1.8 aperture gathers plenty of light. I've used it extensively for Milky Way shots and urban nightscapes - the results are stunning. The build quality is excellent too, and it focuses well in low light when you need it.

Ok so, I just saw this thread and wanted to jump in with a slightly different perspective. When you're out at 2 AM, the last thing you want is gear failure, so I always prioritize RELIABILITY and weather sealing. Night dew or a sudden drop in temperature can really mess with lenses that aren't sealed properly, which is why the S-line stuff is worth the extra cash. I'd suggest looking at the Nikon Z 35mm f/1.8 S. It’s built like a tank and handles harsh conditions way better than the kit lens you're using. It might not be as wide as a 14mm or 20mm, but for city nightscapes, the perspective is beautiful and the f/1.8 aperture is a lifesaver for keeping ISO down. A couple of tips for keeping things reliable out there:
* Primes like the 35mm generally have fewer moving parts than zooms, which basically means less can go wrong over time.
* Definitely download 'PhotoPills'—it's an absolute MUST for planning where the Milky Way will be so you aren't wasting time and battery.
* I also like to check 'Lenstip' for their specific coma and astigmatism tests before buying anything for astro. I'm still figuring out some of the more technical tracking stuff, but honestly, starting with a lens that has solid internal sealing makes the whole experience SO much more stress-free!