I have a Marantz 8805 driving the HT side of our system and couldn't be happier. I have always wanted to try out Anthem as well, both are good choices, so it's all about sound signature and features. I haven't heard the Focals, if they tend to be on the brighter side, I would recommend Marantz.
I have even tried out the 8805 for 2ch music, while it isn't as precise and accurate as a dedicated DAC it is musical and has an immense soundstage. Just a pleasant experience especially if you are used the even warmer McIntosh gear. I was pretty impressed how much you get for the price with the 8805. Their HEOS streaming interface is decent, but quality is great and supports native Tidal and Amazon streaming.
Depending on high up you go in their respective lines, build quality and upgradeability is something to look at. I know Marantz's higher end gear is upgradeable to HDMI 2.1 and are built like tanks. Some of their processors/receiver support recently got updates to support movie/sound formats like IMAX etc.
ARC is better regarded, though I wouldn't count on it to change the sound signature dramatically. From what I have heard, it should fine tune and balance things better than Marantz's Audyssey, especially in a less than ideal room.