Turned out to be a long post here

so forgive me if I’m repeating what others have written already, due to my lack of patience (not reading the entire thing).
I see you mentioned that you like shooting in Manual mode, so you will probably benefit most from a camera with good direct control, that doesn’t have key functions buried in menus. The Nikon D5300 isn’t one of those; I believe it only has one control dial, to change one exposure parameter in Manual mode, and if you want to change the other you have to press and hold the Exposure Compensation button, and then turn the control dial. And you don’t have instant access to changing the ISO. Higher-end cameras, such as the D7200 and D610, have two control dials, so they are a lot more usable in that regard.
In general, cameras nowadays perform a lot better in low light than film ever did. Even sensors that are considered relatively small today, often produce cleaner images than 35mm film. The difference that may make 35mm film favorable is in the nature of the grain/noise that is present: with film it’s grain, that in some situations can actually add to the aesthetic appeal of the image, while digital noise is rarely considered aesthetically appealing.
If you used to shoot in the same low light conditions you plan to shoot in now, and sort of remember the settings you had to use for a good exposure, that might help in determining how low you can go on the sensor-size spectrum before it becomes problematic. I will just assume that APS-C with fast zoom lenses, or Micro Four Thirds with primes, will probably be at least good enough.
There are two approaches to manual control, when there is ample direct physical control: “modern” and “traditional.”
The modern control scheme revolves around unlabeled dials and buttons. Their specific positions have no meaning, it’s all controlled by software. For example, in Manual mode, you can turn the two control dials endlessly, and the feedback you get for what you have selected is in the rear LCD, the viewfinder, and/or the top-mounted LCD (usually an old-school monochrome display), if present. This control scheme theoretically allows for great customization, and a lot of cameras do offer it; I know Olympus offers a great deal of customization, as pretty much every dial or button can be assigned to do any function you want, and you can even choose the direction it goes (do you want to turn the dial to the left to open up the aperture, or to the right?).
The traditional control scheme is based around labeled dials, like the old-school cameras where every button or dial did something mechanically. Fujifilm is probably the only one that really sticks to this approach in its ILCs, and Nikon has that (sort of) with the Df. Fuji’s lenses have aperture rings (the variable-aperture zooms have them, but they’re unlabeled), and the cameras have marked dials for shutter speed, exposure compensation, etc. The flagship X-T1 has the most, of course — it even has dials for ISO, metering modes and some other things. This lets you look down at the camera, see the dials’ positions, and immediately know what settings you have selected. The main downsides are that it limits the degree of customization you can have, and it doesn’t let you instantly change “modes” to quickly get other settings, like you can on the “modern” controls; a lot of cameras let you set a certain pile of settings to one “preset,” which you can enable at anytime and instantly get all those settings, but with the traditional controls, you just have to change them all manually.
With that in mind, I’ll split my recommendations to two: “modern” controls and “traditional” controls. You have to think about what’s best for you, what you’re most comfortable with, and maybe try them in a store / rent via a rental service to compare them.
Modern
I mentioned Olympus before. I do have a bias towards their cameras — after all, I chose one for my own use — but I think it’s warranted. The OM-D series is terrific, and as long as the sensor + lens combination gives you the performance you need, there’s really not much better you can do elsewhere. A common sore point of these cameras is video, which isn’t as good as the competing Panasonic (with the same lens mount) and Sony offerings.
The current mid-range camera in the series is the E-M10 Mark II. It offers great value-for-money, with the same sensor as the higher-end cameras. The next level up is the E-M5 Mark II which, at its current price of $849, I think is an absolute bargain. Add to that the $849 Olympus 12-40mm f/2.8, and you have a decent zoom-based kit for low light.
Other options include the Nikon D7200, Panasonic Lumix DMC-GX8 and Sony α6000. If you shoot a lot of fast moving subjects, especially in low light, the D7200 is by far the best option of this group, and the Canon EOS 7D Mark II may be an even better choice.
Traditional
It really comes down to Fuji here. The two cameras you should be looking at are the X-T10 and X-T1. If the X-T10 has all you really need, and it doesn’t feel uncomfortably small in your hands (it looks to me too small for people with large hands, especially when combined with the bigger Fuji lenses, but I’ve never seen it in the real world), then just save the money and get that instead of the bigger and more expensive X-T1.