From what I read it would probably be Denon. We always had Marantz receivers in our house; first 7007 and then 8xxx series. After about 5 years 7007 died and the other was struck by lightning (through HDMI) this summer. So as the replacement I wanted something not terribly expensive as we only use it for either movies or the morning news radio. Between Marantz and Denon (it is the same company) my wife wanted Marantz. I could not care less, and we picked Marantz sr6015.
I did not realize but from sr6015 on here in Europe there are no Marantz receivers with radio tuner, only with HEOS and internet radio. Boy, do I hate it! Although it sounds quite fine when it works, but it needs to be restarted several times to start playing. If the previous night it was used for TV and in the morning switched to HEOS there will be no sound (although that tiny window will show what is playing, of course). The unit needs to be turned off with selected HEOS channel, and then turned on again. Then it works. Same goes for about every function they put in there, if it is not started the last there will be no sound. It's like it does not pick up change through HDMI, only if it is pre-selected at the start time.
Another thing is the remote. I have several remotes from the previous Marantz models, and they all appear to be more responsive - just snappier than the current sr6015 version. Pressing the buttons feels like something from the 90's, spongy and not very responsive. I do like the large buttons on one hand, but then again, quite many of those buttons have neither inputs nor functions associated with them. Totally useless.
As for the sound, the radio (internet radio) does have a nice tone to it; well rounded, full and quick. As a main system for music however, it is a jack of all trades, neither here nor there. It even has a turntable hookup, I never tried it, but for life of me I could not even imagine why it would be there.
I have not listened to Denon, never had one, but from what have in house now, it would not be Marantz. It is a poorly thought through device.