Hey /p/ so I'm thinking on upgrading my camera (been shooting with a Canon t2i for almost a decade) and I decided I might as well take the leap into full frame. Problem is, I also want a DSLR that can record in 4K since I use my cameras for video related jobs. The only Full Frame cameras that I might buy (either the 6D or the 6D MKIII) don't get that far and only shoot video in Full HD. I could afford one of the lower end ones (250D/SL3 or 850D/t8i) but I don't really see a reason to upgrade for a camera with the same CMOS sensor.

Here's my question: should I give priority to Full Frame (6D MKIII) and make do with FULL HD, or should I instead opt for 4K video with an APS-C camera? I won't me able to buy another camera for a while so I'd also like something to last me as much as my t2i did. I shoot almost the same amount of stills and videos, so it's not a question of wether I do more video or take more pictures. Thanks in advance.