The Realtek boxes all produce a better image than any Amlogic. Deeper colour and a more movie like sharpness. It's like the difference between a good BD player and playing a movie using a Blu-Ray drive in a PC.
The 1619DR chipset in particular produces the best image of any Android based (i.e. in last 10 years) media chipset, on a par with HiSilicon and similar to the very old Sigma Designs boxes (Popcorn Hour, original Dunes).
That's the reason why all the high-end Media Player brands use Realtek and not Amlogic.
As to what to buy, Zidoo use Realtek 1619DR and they have the best firmware (excellent media browsing software and few bugs). They also have a busy support forum, responding to customer feedback with a steady stream of updates. Dune also use Realtek 1619DR and, whilst I appreciate some people prefer their software (not Android and for legacy reasons), their media browsing software is inferior and the firmware is less reliable with fewer options. The new Zapittis use Realtek 1619DR and have good media browsing software, but it's up to the customer whether this justifies the extreme pricing.
The PQ of two media Players should be identical (regardless of the media SOC it uses), or close to identical if it's only up to the reference and the output is intended to be "bitperfect". Difference may only come if this doesn't happen in a sufficient way, or the picture is altered by intention somehow. There are serious tests to measure this, not just saying something about that this and that has more "Cinema like" picture, or "nicer" colors etc... (Like the ones in red shirt in Media Mark selling TV's that have pimped up contrast and color saturation, juts to look more "candy" for the costumers to fall in love at the first glance...)
INCLUDES EXPRESS 2-4 DAY DELIVERY 