From a AML LE developer, Kodi testing perspective:
The ODROID C2 with eMMC flash storage and Gigabit Ethernet is the fastest non HDR S905 device I have seen, because you can give it a slight tickle and overclock it. Quality internal Hardware components from Hardkernel as well. Cases are a bit shabby, but you can hide the box behind the TV or in a cabinet and use with a Wireless remote anyway.
This is my daily driver / Mini PVR LE device because I have a non HDR 10bit 4K TV.
C2 has the best HDMI-CEC of all the AML S9xx LE devices, because of custom AML LE developer work it has had done to it.
Really reliable setup.
Something like a 83,95 € C2 Kit from http://www.pollin.de is all you need for LE unless you have a massive video library.
A eMMC to MicroSD adapter is needed as well when purchasing Hardkernel eMMC flash modules.
The non HDR S905 MINIX U1 is also another quality piece of Kit. Excellent Wireless A2 remote.
The 4K HDR MINIX U9 with its S912 and Gigabit Ethernet is the fastest S912 LE setup I've tested. Quality, properly engineered hardware. Only thing that lets it down is the new A3 MINIX wireless voice remote that has a minor issue with mini delays waking from its sleep function. The older MINIX A2 lite remote has no such issues, its one of my favourite remotes and its batteries last for a good 6 months or more of demanding use.
There is very little speed wise between these two devices when LibreELEC is running from eMMC flash storage using a Wireless remote.
9 second ODROID C2 LE booting from eMMC is the quickest I've seen.
I do not use WiFi for LE use at all. Everything is hardwired for superior LE Kodi responsiveness and reliability.
RPi3 was old, slower hardware when it was first released with a bunch of carry over limitations from the RPi2.
It has been optimised impressively as far as it will go. RPi's have a modern Linux Kernel compared to AMLogic devices if you need comprehensive external USB connectivity to work out of the box with virtually everything.