It is the most value Atmos system you're gonna get that is atleast competent in what it says it does.
There are cheaper systems, but while they may say they do Atmos, they won't be as good.
And there are more expensive systems, that do Atmos better than this, but unless you're spending way more, the difference is miniscule.
C and D are more or less similar in hardware. I think D has HDMI 2.1 pass through while C doesn't, but that's about it.
F on the other hand has a changed subwoofer design. Not sure if it's better or worse though.
E does not exist.