I have never tried the ARCAM, but I have had 4 different ANTHEMS - Sound MUCH better than Denon (which I had), Marantz (which I have had), Onkyo (which I have had - sounds better than Denon or Marantz in my opinion) BUT:
My 1120 the volume got jumpy - traded for AVM 70 (just a total s**t show), they replaced it with a new one, works except one of the outputs for a subwoofer. I have a 520, intermittently performs the HDMI handshake with TV - it is 3 years old. Anthem has good service, and my dealer handles the freight, so I really do not want to try ARCAM because the dealer who sells ARCAM charges to send things in under warranty - I think that is s****y - so check the policy of your dealer. The bottom line - as compared to Onkyo, Denon, and Marantz - there is just no contest. The sound is absolutely incredible - they just are not the most durable things on the planet.