Then again some of us have had very good experiences with Denon (& Marantz since they're sharing most things but marketing angle). So I will inject perhaps a different viewpoint.
Denon does not have MusicCast at all, it has Heos (and have read of more problems using MusicCast than Heos generally). I've used the IP control for Denon without issue, altho the android app for using your phone as a remote that Denon provided wasn't the best (and for older models there was an alternative private app that worked better too), but I use a Harmony remote so not a big issue for me at least. I don't think various music service type apps installed on the avr itself have been particularly superior on Yamaha over other providers from what I've read.
As far as apps go, the Audyssey app does put it in a different league from YPAO; parametric EQ Denon doesn't have but perhaps doesn't need as much as a result of the better program (altho it perhaps would be nice to have parametric eq on board as an option). Whether or not you wish to use a roomeq type program at all is something else, some don't like any eq at all (let alone a tweaker of bass eq like ADTG, a former Denon promoter but upset that his ridiculously priced and unique pre-pro couldn't be fixed, not to say that's not an issue, just not an issue many experienced as few had that particular unit and Denon doesn't even offer a pre-pro any more except for a very basic stripped down "pro" version).
HDMI/HDCP issues are still going to be a potential problem unless you use all Yamaha branded gear, but hasn't been a particular issue much with Denon that I've read about (or experienced) and most of the issues about HDMI use seem to be generally just a mixing of various brands that don't follow the same implementation of HDMI-CEC particularly (such as ARC, which is fairly useless to begin with IMO). Can't say I've read about any HDCP issues particularly at all.
Denon is usually more competitively priced for the feature set (and sometimes Marantz, altho generally Denon pricing is better than Marantz at least in the US). Yamaha has had some issues with pre-out levels and over zealous protection schemes too (e.g. see
Audioholics review of A860). Yamaha uses odd terminology to describe several functions compared to others, too.
I'd wager the reliability issue is marginally different for Yamaha rather than greatly different (nature of consumer electronics generally), and have read about issues with Yamaha units as well as others. Mcode doesn't really share his in-industry survey details on which he bases his reliability info, so hard to know just what the numbers are or how they're compiled and based. Who cares about people who can't operate or install their own systems? (not really serious, but personally don't even understand why someone couldn't plug a component in and set it up themselves, especially those willing to dig into a forum like this).
Yamaha does have better corporate/financial stability the last several years and controls their manufacturing more in-house; we'll see if Sound United can't improve on the past coupla owners of Denon/Marantz brands.
I still say pick an avr based on features you want at a price you want. If a refurb, A4L will pay return freight on defective refurbs (certainly a risk to think about and have experienced such myself), but they are not a good place to shop if you're a fickle consumer and simply want to return something for free because you changed your mind (definitely some other retailers have an advantage here with satisfaction guarantees across the board, but they're not quite in the same market as A4L either).
Just my take on it....