I really like Sony having owned the A7RII & A6300 for a while, but I also like Canon.
The R6 & Sony A7SIII are 10 bit 4:2:2, but only the Sony can shoot RAW, 16-Bit RAW actually. Atomos just need to do their bit, and we need to see more evidence of the raw quality taking place.
The Sony is also 15 Stops of DR, has a range of log formats and HLG as well as good AF from what I've seen so far. Also rolling shutter looks good too.
Adapting EF Lenses to Sony should be fine with the improved AF...you could wait to see more tests. I was initially going to get the A7SIII, but I'm not too snagged up about the price. I always used EF lenses on my Sony like the Sigma ART 30mm F1.4 and Canon 50mm F1.2L, manual though. Great colours.
If you need raw, Sony has the upper hand, otherwise the 5D3 + R6 Could be a good combo (Best of Both World's). Hopefully they can somehow fix the overheating through an update or something, otherwise they're fried! 😉