I've narrowed it down but...

I was wondering about the low power of Marantz. The Denon would be a better choice of these w/ almost double the power and ability to drive lower impedance.

Have you seen this review on the Denon?

http://www.soundvisionreview.com/hi-fi-home-theater/amplifiers-receivers/denon-avr-x2100w-review/

I read that one, but others gave it a very good review. Makes you wonder. Maybe I should look at the Yamaha and Marantz more seriously.

I'm having issues with Denon's website, so I can't be specific, but if you can afford it, consider getting a model with pre-outs available.  Then you can get an amp later.

I've owned three lowish end (<$1000) Marantz and two Denon.  The three Marantz all had problems.  The first spent roughly 6 weeks in the shop during the first year, and Marantz was nice enough to finally upgrade me to the next model up.  Then that one eventually failed in one of the surround channels (I still used it for a while in Stereo in a different room).  I then switched to Denon based on a recommendation and was quite pleased.  I had no issues, but after upgrading speakers, I needed an amp to drive them and my Denon didn't have pre-out.  So I bought a Marantz again because it had pre-outs at a cheaper price point than Denon (and i'm pretty sure at this point Marantz and Denon are owned by same company?).  Within days, I was having problems with the Marantz spontaneously changing input sources.  So I returned it and bought a more expensive Denon with pre-outs. 

So, in terms of reliability, I've personally had better luck with Denon.  In terms of features, if you may want to add an amp in the near future, try to get a receiver with pre-outs.

If your primary use is for video, I'm not so sure that ultimate sound quality is all that important for a couple of reasons- first, I think we are primarily visual animals and so the video quality dominates our sensory expericne.  Second, I don't think most video content providers put much of a premium on the audio portion of their content delivery.  I will tell you that my Marantz SR 5006 sounds WAY less powerful than its 100 wpc rating.  If I had to do it over again, I'd have gone for more power.