I think the author would do well to shed some of the "SPEC" comparison urge as this really leads to nowhere. Go to youtube and compare major app load-times comparison video where the author compared the iPhone6, The HTC M8, and the Samsung Galaxy S5. The last two have a quad core, and an octal core processor with 3 or 4 Gb of RAM.
The iPhone6 was ahead by a considerable margin on both of those devices. One can also go out and read reviews on METAL and how it is improving graphic performance on those apps that are using it. "OPTIMIZATION" is much more difficult to obtain and requires a very tight control over hardware, and software and being disciplined enough to say " I will not keep bumping up spec for the sake of it and reduce my performance".
Even without a quad HD screen the iP6 and 6+ is ranked at the top 2 or 3 devices as far as displays are concerned. What is then the point of having such a high pixel dense screen that ultimately saps too much power form the device reducing battery and performance? Just to sell more phones? How is it that even with these features those devices that are now looking at even more pixels actually have a lower profit margin? Buyers aren’t fools that they will read about a gazillion pixels and buy a phone just because. Same applies to the camera. It is well established that the pixel count contributes roughly a 1/3 of the overall quality, yet many OEM"s are guilty of almost solely focusing on this aspect.
The A8 is a very efficient SOC that takes the iPhone performance to the highest level in mobile phones. As has been shown its bigger brother in the 8X on the iPad Air 2 is currently benchmarked as the most powerful tablet in the world with a very significant speed bump from last years iPAD AIR. Where the A8 also scores is that it is the second generation 64 bit chip meant for an OS that actually has 64 bit ecosystem in place. Other devices are shipping out chips without having the OS catch up and one would assume that this " tail wagging the dog" will continue for a year or two given how fragmented Android’s eco system is. The design that emphasized the thin"ness of the phone is the show stopper for me. I would have hated a scaled up iP5 as the overall form factor with a larger size would have meant that it is too uncomfortable to hold and operate. Size here isn’t just thickness, but how thickness directly impacts weight that ultimately impacts UX while operating it. This is where the 5+ inch M8 looses despite of having what is widely recognized as the best Industrial design among android flagships. It is heavy, and thick and not too different form the older HTC One. As a comparison my 4.7 inch iPhone 6 with a Spigen case is still slimmer than my Nexus 5(a great phone btw) without the case. and even with the case(feather) the phone is still lighter than the iPhone 5s which was a smaller form factor. Can;t deny that this impacts UX and how one receives the size/form factor bump.