^HDMI 2.0 is all I'm aware of, of possible significance. But even with 4K, it may not be necessary for years and will likely introduce more growing pains. Unless you need 2.0 now or see yourself needing it sooner than you can afford to upgrade your AVR again, steering clear might even be advisable.
To elaborate on the above posters statement, the Denon would be the better choice if auto-room correction is of chief concern, as Yamaha's YPAO is likely (not definitively, but likely) inferior, or at least less aggressive than, Audyssey XT32, which some people actually favor the Yamaha for, though I'm not sure I'm one of them, having recently switched from a Denon with XT to a Yamaha 3030. Yamaha specializes more in manual EQ, which the 3030 would be a much better choice if you don't trust the accuracy of auto-EQ or prefer to tailor the room EQ more personally.
I think Audyssey is also geared more for movies than music. Many prefer to turn Audyssey off for 2-channel music listening - though it might be more desirable for concerts recorded in multi-channel surround. If movies are your primary goal and you're not very familiar with EQ and want something with a more minor learning curve, Audyssey XT32 is probably what you want.
If so, I'd, personally look closely at the Marantz 7008 over the Denon, but that's partly a subjective choice. Both feature XT32. But if you're going to use an external amp for the most demanding channels anyway, you probably don't need the extra power of the 4520, which is it's main selling point over most others around its pricepoint.
