What's stopping you making a decision & taking the plunge?
I think I have an unfounded bias against buying Marantz, where Audyssey appears to have a reputation for being a bit ‘Mickey Mouse’ compared to the alternatives (Dirac, ARC, Room Perfect, and Optimiser).
Even so, there are very positive reports about buying/implementing
Audyssey MultEQ-X - with a $200 price tag from the Microsoft Store: for a single Processor that is non-transferable. Compared to the standard Audyssey, the MultEQ-X software provides a substantive ‘night and day’ improvement to any compatible Marantz Processor/AVR.
Then again, unlike the competition, Marantz kit seems to have a rock-solid reputation for just working out-of-the box without any of the drama of software glitches that plague other brands.
Plus, besides the recent HDMI 2.1 upgrades for Marantz, JBL, and Anthem, there have not been any completely new products since the start of the pandemic. I’m in no hurry. I’m prepared to sit it out and await any possible new products during Autumn/Winter - such as a Rotel Diamond Processor (with Dirac), for example.