I have not seen such an easy to answer question for a long time. It is indeed very specific when you say you want it to get as close to......Anthem.....!!
There are two facts that are highly likely relevant to the audio performance of the MRX520:
1) Relatively high distortions relative to other Denon and Marantz AVRs (since those are on your short list).
2) The fact that Anthem mission statements say"
Based on these known facts, I would say if you can stretch your budget, the X4800H is the winner for you, if not, the X3800H should be good, but not the Cinema 60 unless it costs less than the X3800H. The comparable Marantz to the X3800H is the Cinema 50, so if in Europe the Cinema 50 may be a better choice.
Now take a look of the sources of the facts I listed above:
On Anthem sound quality signature:
Frequently Asked Questions | Anthem® (anthemav.com)
So, if you like the "sound quality" of your MRX520, it is most likely that you like the sound quality of everything else especially the quality of the source contents you normally listen to, not the AVR itself as the MRX520 would just stay out of the way.
On fidelity, say based on distortions + noise:
Note that at one point, the one year newer model, the MRX520 ranked last of all AVRs measured on ASR, even below the NAD T758 V3.
However, at 0.06% distortions+noise (1 kHz test signal, 5 W into 4 ohms, or 2.5 W into 8 ohms, is still going to be below the threshold of audibility for normal people. Caution: that's for 1 kHz test signal, at higher frequencies such as 5 kHz, 10 KHz, expect distortions will go up but should still be well below 1% so that will still likely not give the impression that it has a different "sound" that others.
Note: The graph below compared the power amp distortions plus noise. If used as preamp/dac, the MRX520 would have ranked much higher, not far behind the Denon AVR-X3700H and the MRX-1120.
For more details, please read the review and the complete test results:
Review and Measurements of Anthem MRX 520 AVR | Audio Science Review (ASR) Forum
View attachment 65450
If you can live with Denon's style, and if you are in North America, go with Denon and avoid Marantz unless you don't mind paying a heavy premium for the look. If in Europe the price differences between the two name brands won't be much unless $200 more just for the name tag and aesthetic is still too much for you.
Onkyo RZ50 looks viable to me too. If you have only one sub, the MRX740 has great specs and performed very well on the test bench, probably among the best of any current AVRs.