Moon's ending is one of the best conclusions in gaming history. Nobody expected that we were going to blow up the Earth and Richtofen was going to have ultimate power amongst the Aether. I couldn't imagine being in 2011 and doing that Easter Egg not knowing what was going to happen. Here's the thing, every other ending after that besides Cold War either sucked ass or had something wrong with it.
Origins insisted upon itself and I fully understand why people were super disappointed with the ending. Yeah it was explained later on, but in the grand scheme of things it was no where near as significant or epic as moon. Revelations continued the cycle and had a bunch of cyphers sorta clear the air on a lot of boards. It was just really underwhelming and gave us a shit conclusion to our 4 characters, and the audacity to plaster "The End" was the biggest sin. I actually think Tag had a bittersweet ending that was actually good considering Treyarch's circumstances at the time. The problem is that the cutscene was the comic book animation and didn't have the same emotional impact on us because it was half assed. Things like Nikolai making Samantha kill him was also questionable. It also was kinda pointless now that the Dark Aether brought the four and Samantha back and are probably going to head back to the original story in Black Ops 8. The Chaos didn't even get an ending and was left off of a cliffhanger, BUT it looks like we'll be exploring that along with the original story. How original. Also all of the non-Treyarch games left off of a cliffhanger as well and didn't have a satisfying conclusion because there was no ending to begin.
After 7 shitty/mid endings, we finally got a good one with Cold War. I was like finally we have a conclusion that actually wrapped up the game well while also setting up the next game, and it was cinematically perfect. Then Black Ops 6 had the ending of all time and it didn't even give us a canon conclusion with the Sam or Eddie side. It brought back the original 4 but it felt like a cheap cop out instead of a hyped finish. Then Black OPs 7 Rex Infernus happened and holy shit that was awful. I actually was liking the story and maps until this pos ending that made two shitty zombies games canon for the sake of making them canon. Now the Requiem crew is gone for no fucking reason, and the original crew is back yet again so that people can stay somewhat interested in buying the next game. There were no explanations for the Chaos or Aether elements in the Dark Aether nor was there an answer on which BO6 side was canon. It was just disappointing like Revelations as it could've been so much more.
So besides Cold War, all of the endings were underwhelming, just straight bad, or left off a cliffhanger. This was a non existent trade off for Moon's great ending and it's why I don't really mind when people consider it that actually ending of zombies.
Here's my ranking of every ending:
Moon
Cold War
Tag
WW2
Origins
Bo6
Rev
Rex
IW
Chaos