I have a few of the cheaper Android boxes a couple 905X2 and a couple 905X3, then i have an H6 Allwinner, and aS912 i actually think the S912 has a better image then the others.
Ive seen the benchmarks and everything but imo the 905 units look grainier but they are faster, the S912 looks cleaner the lines look smoother to my eye then the 2 905 versions but the 912 is slightly slower
But they arnt the Khadas units so its hard to say if they will be the same as the cheaper chinese android boxes i have