I loved Cubicle 7's AIME and I hope to try out Wrath and Glory sometime.
The network effect with d20 and DnD is huge though. Best support, richest ecosystem, most players who are willing to read the actual rules. That's been the biggest stumbling block on trying other systems. People get home from work and don't want to... work more. And reading rules feels like work.
You nailled it. I enjoy all Warhammer 40,000 games because I already know the lore, so Cubicle7's version in the new Imperium Nihilus matches the new lore with the fall of Cadia and the galactic rift. As for the d6 dice pool mechanics, dice roll like Blades in the Dark.
Similarly, Cubicle7's currentl Warhammer Fantasy Roleplay uses the known d100 system of first edition and I also know its lore including "The Enemy Within" campaign arc.
So this leaves the Age of Sigmar Mortal Realms the unwanted guest at my table party. Do not know the lore, the d6 character sheet looks different from Cubicle7's Wrath and Glory, hence, seems like too much work for my table.
Addendum to some recent comments. Yes, it is poosible to learn new RPGs. People do that daily. And yet game engines are popular because Re-using pre-existing knowledge is easier than all new stuff. Hence, I look upon the awesome free Degenesis RPG, got the core book, perused it, but then just said, no, too much new lore, even though dice mechanics look okay.
Contrast the above to Fria Ligan's (Free League), Year Zero Engine, award winning alongside well established Aliens IP, and, boom, runaway success with GMs and Players.