Hi folks currently use a EOS 1300D, im looking to upgrade for better pic quality, occasionally do video but that's not important. I mainly shoot landscape but like some lunar and aurora when it's clear and strong enough to see. Also like wildlife occasionally.

I'm mainly looking at used as unable to get finance, with a budget of £500-900. I'm keen on jumping to full frame for the low light capabilities. Mainly looking at the 5dmk4 but wondering if there's other cameras worth looking at? Doubt there's any mirrorless for that amount but I'm open to slightly future proofing aswell with going mirrorless.

Since I'm used to it would rather stick to canon.