I have the older 6500 and wouldn't trade it for the world, except to a newer model. It is a workhorse that does Atmos 7.1.4 great for me. I've actually held off on upgrading the video side of things in the basement because I'll want an HDMI 2.1 solution that the 6500 can't do.
Going down the...
I’m on travel today but will add thoughts tomorrow.
I personally only use and recommend Denon receivers tho, so that will be my main advice. They are comparatively expensive because they are worth it.