Canon - EOS R1 vs Sony - α9 III

These two are evenly matched on the broad strokes, with the decision sitting on which individual spec advantages weigh more for your use.

Pick the EOS R1 if you care most about af points and max video. The biggest gaps in its favor are af points, max video.

Pick the α9 III if you carry the device everywhere and weight or thickness has been the deciding factor before. Its strongest claims are weight.

Both ship with comparable sensor size, megapixels, in-body stabilization, so those specs don't separate the two — focus on the differences below.

Bottom line: there is no wrong answer here — match the spec advantages to how you actually use the product. The Mars Score parity tells you both are well-rounded; the differences are about trade-offs, not quality.