My opinion based on having read all the reviews...
I don't think Amir ever "raved" about any AVR, including Denons. The choice of which Denon model you buy should primarily be driven by your needs. For instance, if you have a relatively small room and a 5.1 or 7.1/2 setup then an X2600/X2700 might be the best choice. Paying the extra for an X3600/X3700 will give you more channels, power, and features that you may never use/need.
It's a bit like buying a car with a 3.6L engine over the same car with a 2.4L engine. If you only ever have a couple of people in your car and you never need to tow a trailer then the why pay more for the 3.6L version and the extra gas it will drink? Of course, you may just like stamping on the gas from time to time and leaving others in the dust, in which case you might decide on the 3.6L.
As for the choice between the X3600 and X3700, they are basically the same thing but X3700 gives you a few more features such as support for 8K video. All things being equal, the X3700 would be the obvious choice, but if you can find the X3600 considerably cheaper than the X3700 then that could be the one for you if you want to save money. At this point though, I am not seeing the X3600 being considerably cheaper, unless you can find one in the used market.
I would also add that issues identified in Amir's audio quality tests are often not audible to most human beings. Amir normally points this out. So while the X3600 may have tested marginally better than the X3700 in some areas, in real life use there would likely be no perceivable difference between the two.
As a final point, I have found that AVS is not a place to ask people to make decisions for you. The whole point of the place is to provide you with enough data that you can make informed decisions yourself. I'm betting I know no more about AVRs than you do but after a few months of reading thru these forums I feel I am able to make better buying decisions in some areas, AVR being one. In fact, I ended up cancelling my Denon X3700 order and buying a Yamaha TSR-7850 for a fraction of the price. I am sure the Yamaha would not perform as well under test as the Denon, but it meets my needs perfectly and at a price I'm happy to pay.