Warning: dont chase “sharpest center” charts—corner consistency + flare control will bite you on travel. I’d suggest a Sigma Art prime in the ~35–50 range; mine’s been CRAZY even edge-to-edge, low CA, reliable AF.

+1

Late to the party but same setup here (S5 II) and I went through this exact rabbit hole… I ended up living on the Sigma 35mm f/2 DG DN Contemporary (L-Mount). Not the “sexiest” on paper, but in actual travel/portraits it’s been fantastic:
- corners stay surprisingly clean stopped down
- flare is pretty controlled for street/night
- CA/fringing is lowkey minimal
- AF has been pretty reliable on my body
Plus it’s not crazy $$$ so it felt like max IQ per dollar. cheers!

Warning first: dont pick your “one go-to” based on lab charts or a single copy review. Sample variation + decentering will straight-up wreck corner-to-corner IQ, and you won’t notice until you’re home zooming into brick walls from a trip… so buy from somewhere with easy returns and actually test corners + flare on day 1.

- Option A: a top-tier native Panasonic zoom (the “pro” line). Pros: usually the most consistent across the frame, strong coatings for flare, and on the S5 II the AF behavior is typically the least weird (tracking + transitions just work). Cons: bigger/$$$, and zooms can have more field curvature so “corners” depend on your focus distance.

- Option B: a premium Sigma prime (Art-ish vibe). Pros: high micro-contrast, strong CA control, great sharpness even wide-ish. Cons: some copies vary, and some primes can get nervous in backlight (purple fringing / veiling) if you push it.

- Option C: compact primes (any brand). Pros: travel-friendly, decent value. Cons: corners and flare control are often the first thing they compromise.

If you want safest “buy once” all-rounder, I’d lean native pro zoom for reliability + coatings, then add a prime later if you miss the look. Cheers, gl!

So yeah, I totally agree with the warning about sample variation—it’s a real headache when you get a copy that’s soft on one side. But like, I’m curious, are you the type who likes to tinker with your gear or do you want a "set it and forget it" experience? I mean, honestly, some brands let you do your own firmware updates and even some basic tuning via a dock at home, which is pretty great if you’re a DIY person and don’t want to deal with professional service centers every time there’s a minor glitch. I'm pretty sure it saves a lot of downtime if you can handle the maintenance yourself. But wait, before you go for the absolute "best" IQ, how much weight are you realy willing to lug around for street and travel? Like, would you be okay with a massive lens if it meant zero corner smearing, or is being low-key more important to you? Definitly something to think about before dropping the cash.

@Reply #5 - good point! I actually went down the DIY rabbit hole myself because I couldnt justify the price of the Leica glass but wanted that clinical edge-to-edge performance. I found that buying used Sigma Contemporary lenses and using the Sigma USB Dock UD-11 L-Mount to keep the firmware current and tweak the AF behavior saved me nearly a thousand bucks compared to buying new Art or S-Pro lenses. I have been running the Sigma 65mm f/2 DG DN Contemporary L-Mount lately and the micro-contrast is genuinely insane for the price. To get that top-tier IQ on a budget:

• Scour the used market for I-series lenses which are built like tanks.
• Use the dock to customize the focus ring feel... makes a huge difference for street shooting.
• Perform your own decentering tests with a distant landscape shot to ensure you got a good copy. Its kinda satisfying knowing youve optimized the gear yourself without paying the luxury tax tho. Just make sure you check the lens mounting plate for any play before the return window closes, as that can mess with your corner sharpness data.