Struggling to decide between camera systems. Which do you have experience with? Which do you think is better?

I've been shooting M43 for a while now after upgrading from my phone camera. Really love the experience of holding a camera and the tactile experience of the knobs and aperture and zoom ring etc. But my current camera isn't quite good enough in a couple of ways:

  • It's too small. I'm tall and have big hands, I bought my small camera cause I wanted it to be more or less pocketable and that it is, but for actual photography outings where I'm not just throwing something small into my bag as a contingency it's too small and my hands cramp-up, it doesn't have enough controls so I constantly need to go into the menu for basic settings if I'm not shooting full-auto and the few controls it does have are really easy to accidentally bump when the body is already too small for you.
  • Low-light performance is just not good enough. I shoot a lot of travel photography and don't always get to choose when I show up somewhere because my partner and I do lots of cheap rail travel and weekend city hopping through Europe rather than destination travel for 1-2 weeks. I need a camera that can get usable levels of noise in any basically any situation
  • Dynamic range could be better. It's really not bad, but sometimes the files I get are a bit flat. Could also be my fault / the lighting I shoot in though, so this is a distant 3rd.

I haven't invested much into my current kit and it wouldn't hurt me to sell it or keep it as a backup. I bought most of it used for relatively cheap. I've been to my local camera store and tried a number of cameras and lenses and I'm still kind of split in the middle between Fuji and Nikon. I also considered the OM5 and OM1 but in the end the OM5 was too small and in both cases I'm worried the MFT sensor will struggle when I need it to perform especially in low-light. I love the retro look and I'm looking at the ZF and XT5 specifically and I can't decide. Even after holding both I'm just not sure and don't know if I really could be without taking them each on a trip which I can't really do unless I drop a few hundred € on rentals just to walk around my town and test them out. Youtube videos haven't been too helpful either

Besides the retro look, tactile controls and all the stuff they share here are the things I'm thinking about with each kit

Points for Nikon:

  • Full-frame but "only" 24MP so it has really good low-light performance according to everything I've seen, heard and read.
  • Really good for adapting older lenses and using manual-focus lenses. The tactile experience being one of the things that's drawn me to cameras instead of phones in the first place I really like the idea of buying a manual-focus lens
  • I can "upgrade" to a flagship FF camera and use the same lenses. I have been asked a couple times to do professional shoots both paid and unpaid and I've had to turn them down cause I don't trust my gear to deliver 100% in terms of IQ, low-light indoors etc. So any money I spend on lenses will be money well spent
  • Great glass in terms of IQ, but it can be really large and pricey
  • Physically larger, more robust build as well

Points for Fuji:

  • The sensor is 40MP but it's also APS-C so it's (probably?) going to have worse low-light performance. This is kind of my biggest worry. I'll more than likely get great shots from both cameras, but the IQ generally on the ZF is much better and the files are better to work with as well, which I do enjoy doing
  • More travel friendly. While it's smaller than the Nikon which isn't necessarily a plus for me, bigger than my Lumix G100 it's lighter and the lenses are way, way lighter. I made a theoretical kit for each of them with a wide-angel, 50mm and zoom lense in a spreadsheet and the comprable Fuji lenses are often less than half the weight and cheaper too. The only way I could get the kits "balanced" was to add crazy telephoto lenses to the Fuji kit
  • But, if I invest in Fuji kit and wind up doing any sort of professional work I will have to reinvest in another kit to do that with
  • It's more ergonomic. But honestly that's not too important to me I found the Nikon to be usable and there are grips I could buy as well
  • I don't care about film recipes, I do that myself after the fact. But who knows maybe I'd learn to love them in practice and convert

Do any of you have experience with these two? What do you prefer?