exynos was ignored by developers mostly because samsung havent provided proper documentation, sources etc.. it has nothing to do with the architecture
and the a57+a53 is 64bit and it has been implemented only in the recent note 4 variant, samsung adopted the big little architecture earlier than everyone but their implementation was far from perfect, like throttling issue, poor optimisation,mediocre gpu etc, (compared to SD), over the course of time they have managed to solve the issues little by little which is evident in the benchmarks ,you had posted in the OP,
now what you need to remember is these soc have HMP enabled ,which probably means almost all the cores are active when the benchmarks are done, which is never a real usage scenario and there is almost a 50% drop after a certain period of time ,which can affect perfromance in daily life
qualcomm on the other hand . i believe waited enough for this new architecture to mature and release it
Now my point is i dont see any advantage you can have over SD when compared to the exynos variant ,except for the wolfson dac
in fact if you look at the cons against pros , the balance is in SD's favour,right now, perhaps it could swing in the future, who knows
Well let me see if anandtech has done any benchmarks on them or wait for them to.. a more definitive verdict can be reached then