The Marantz would be my choice as you will get a cleaner fuller sound combined with your amps and speakers. The Onkyo might be a touch forward with the NAD power. I am yet to hear the Rotel but as a brand it is quite forward, I have plenty of experience with the outgoing 10 series. The Marantz is in a different league IMO.
If you can live without HD audio and video processing (or if you have a Blu Ray player which can handle this for you) the AV9 might be a good choice. Seven Oaks are selling them off for ~£1,500 right now.