Just get the Fujifilm XF 23mm f/1.4 R LM WR and dont look back! I love it because its absolutely fantastic on that 40MP sensor. Honestly, the old f2 just cant resolve the detail like this one does.

• The linear motor is insanely fast for street shots.
• Glass is specifically designed for high-res bodies tho.
• Fully weather sealed for those rainy London days. Its amazing glass, grab it!

To add to the point above: it seems like the group is pointing you toward the new 1.4 glass, and I totally agree. I've tried many different combos over the years and found that the X-T5 sensor is just too sharp for those older lenses to keep up. If you want to feel safe about your gear choices, upgrading to the new trio is the most sensible move. The Fujifilm XF 23mm f/1.4 R LM WR is basically the gold standard for what you're doing. It hits that $900 budget almost exactly, tho buying used from a reputable place is a great way to save some cash. I'm always worried about the rain in London, so having that WR badge gives a lot of peace of mind. It's a reliable setup that wont let you down when you're trying to capture a quick moment.

Saw this earlier but just getting home to check my notes. Honestly, the 40MP sensor is a total beast that demands high-end optics to really shine! I had the exact same frustration when I upgraded my kit last year and realized my older glass just looked muddy. TL;DR: The Fujifilm XF 33mm f/1.4 R LM WR is the optical benchmark for the X-T5 if you can handle the tighter focal length. It is absolutely incredible for detail! My journey involved testing almost every prime in the lineup because I was worried about weather sealing failure in the field. I eventually landed on the 33mm f/1.4. The technical design is superior because it uses a Linear Motor (LM) for near-instant silent autofocus, which is a massive reliability upgrade over the old DC motors. From a data perspective, the resolution throughput is specifically optimized for the high pixel density of that X-Trans 5 sensor. The 15-element construction includes two aspherical and three ED elements to kill fringing. Plus, the build quality is fantastic for street work. The weather sealing is robust with seals at nine points on the barrel. I have used it during heavy downpours in the city and never had a single malfunction. It feels way more durable than the f2 series. If you want that peace of mind while shooting street in messy weather, this is the one!

Like someone mentioned, that 23mm 1.4 WR is a tank. But if you want something wider for cramped London streets, look at the Fujifilm XF 18mm f/1.4 R LM WR. In my experience, its actually the sharpest of the new trio on the 40MP sensor. AF is instant. Really great for candids. Its well under your 900 buck budget if you shop around... honestly dont sleep on it.