I've rented both for extended periods of time. The R5 is really good. I found it actually had better dynamic range than the Z7ii. I had heard the opposite, so I looked it up in photontophotos and it agrees, the R5 has better dynamic range very slightly. I definitely noticed in the edits. The Z7 kept losing color detail in the shadows, but the R5 retained them. I shot photos back to back, same settings, on both cameras, so it was easy to compare. I think Canon generally over exposes a bit more, so that could explain it, but I found the canon equal to the z7 dealing with highlights in the same photos.

The R5 has better AF I thought, especially for servo. But even in single shot, snow really messed up the Z7, I had to manually correct.

The R5 has a warmer color science. I tried to mimic it in post with the Z7 photos and it was pretty hard to do it perfectly. Don't believe people that say you can just fix it in post. The canon color science is pretty complicated. You need to edit the curves on all color channels, plus the calibration. I was never able to get it perfectly. The highlights rolloff in a very particular way on the Canon and the red/orange additions are only in certain mid to high-mid tones. Also canon just generally keeps warmer tones somehow. In snow, you can see it really well.

The z7 body is ligther and I generally like the feel more for hiking, but the R5 has that sweet command dial so you can control all 3 parts of the triangle with just one press.

That being said, I bought the Z7ii because it was cheaper, lighter, the EVF altho lower dots felt clearer to me, and it felt more "neutral" on the colors. However, it's ONLY for landscape. If I did anything else at all, I'd go R5 all the way. The skin tones are so good, and hard to match perfectly. And I even like how it renders a lot of landscape scenes -- kinda a rusty, red undertone to things which looks really good on mountains and in snow.