Im not buying that the Marantz is going to shine over the Arcam or Nad for sonics from it's analog and amp sections, honestly. In that respect, I'd prob say the Arcam is the best sounding unit, on it's own. But I'm assuming.
If you don't need the room EQ so much, I'd recommend Arcam's products. If you measure the room to have lots of peaks in the bass response up to 300hz, I'd consider the Marantz, and wait for a deal on a multi channel amp or stereo for the front 2 ch, at least. I find your amp sections in these mass marketed Denon's, Yamaha's, Marantz's, Sony's, and the likes to have marginal amp sections. In this genre, I like the HK's over the years, then the Denon's, for your standard Chinese AV receiver assembled fair.
My prob, again, with the ARcam, is no room EQ, which can DEFINITELY help level playing fields, make of for sonic nightmare issues, and make a much more accurate response acccross the spectrum, deal with some acoustics Issues, etc. Not so with the Nad and Arcam. You really need to add an EQ in the subs, at very least, and be extensively careful in set up for rest of the speakers if you don't gots no EQ - cause even large living rooms have lots of modes that need knocking down, with limited placement and seating options (especially with a wife-unit to appease).
But, all things on their own, I go Arcam, then the Nad, likely, then other receivers down the line.
