>>4115569>1. How important is full frame over apsc for low light photography? (Primarily shitty night street shit you've seen a million times but less light because I don't live in a city)Depends how sensitive to noise you are. I do lots of low light shooting on APS-C and it does great for me. Full frame really won't get you that much more light, it mostly just reduces the amount of noise.
>2. What would everyone's recommendations be for a really budget low light camera? Priority number one would be build quality. Priority two would be size, but I know DSLRs are way cheaper than mirrorless in this aspect so I'm unsure.Older, cheaper DSLRs may have issues with high ISO performance, I think you'll want a pretty modern camera with back side illumination whether you go mirrored or mirrorless. I would go mirrored simply because you can preview your shot in the EVF, which I find helpful for low light rather than taking it and checking after with a DSLR. Sony has a good reputation for low light. My Fuji does well. Probably lots of good options.
>3. M43 is too small for that kind of shooting right? I mean I know they have IBIS but...It depends. Aside from noise performance sensor size is going to give you more dynamic range, that is the number of 'steps' you can have between the brightest object in frame and the darkest object in frame) the more steps the nicer the transition from dark to bright. I'm sure there are plenty of people who do low light with M43, it all depends on your pocket size really, spend more money get technically better photos, but technical superiority doesn't mean an image is better. You just have more room for error and typically a cleaner image, if that sort of thing matters to you go ahead.
Personally I would go FF if I could afford it for low light, but it's not realistic for me. On the other hand it's also not actually limiting my photography.