Large crossover events in comic books can go one of two ways. They're either mind-blowing stories that change the status quo, successfully altering the world in a way that's satisfying to both long term fans and neophytes. The other way is an absolute train wreck. However things turn out, these stories are rarely mediocre.
Unfortunately, the absolute train wreck option is the outcome all too often, as was the case with Marvel's Civil War II and Secret Empire. But each one could be seen as the worst of its era for very different reasons.
10 CIVIL WAR II: Unexpected Early Deaths
One of the most heart-wrenching moments in the Civil War II was the unexpected death of War Machine at the hands of a rampaging Thanos. It was a battle that also mortally wounded She-Hulk. This was an unexpected turn of events that happened extremely early in the event. War Machine and She-Hulk were, and are, two fan favorite characters. It made for a stunning moment but sacrificing them in such a manner to serve the story for shock value was hollow at best.
9 SECRET EMPIRE: Black Widow Dies
Not to be outdone, Secret Empire had its fair share of casualties, too. Possibly the biggest was Black Widow, a character Marvel seems to have a continuing issue with sacrificing to stories in the comics and in the movies.
In Secret Empire, she was killed by Hydra Supreme. Like War Machine and She-Hulk, her death was somewhat cavalier given the nature of the moment but at least Black Widow got to contribute for a few issues before she died.
8 CIVIL WAR II: Future Crimes Fight
The crux of the fight in Civil War II was essentially over the plot of the movie Minority Report. A new Inhuman had the ability to see major events before they happened, like the Minority Report PreCrime Division. Captain Marvel was all for the idea while Iron Man was against it as he felt it was immoral.
The problem with that was it seemed opposite to how they should have felt about the situation. Iron Man has always been a futurist, looking for any kind of new technology or edge. Him being against using this new resource simply did not make sense.
7 SECRET EMPIRE: Started Strong, Finished Weak
The first few issues of Secret Empire were reasonably good, due in no small part to the massive Captain America twist that kicked the whole story off. But as the story went on, it fell further and further apart, leading to a resolution that was surprisingly predictable.
Even evidence of Black Widow's survival pops up, though the eventual reveal was that clones of her were running around. The story didn't deliver on the promise made by its opening moments.
6 CIVIL WAR II: Killing The Hulk
Civil War II was bad for the Hulk family in general. First, She-Hulk was sacrificed to the story and then Hulk was. Ulysses, the Inhuman with precognitive abilities, had a vision of Hulk killing the Avengers. Captain Marvel decided to confront Bruce Banner about it but before anything could happen Hawkeye killed Banner with a well-placed arrow. This was apparently at the request of Banner who wanted Hawkeye to kill him if he ever lost control. Like other heroes in the story, it was an unceremonious end for one of Marvel's biggest characters.
5 SECRET EMPIRE: Captain America, Hydra Agent
The biggest twist of the entire story was that Captain America had been a Hydra agent all along. Naturally, that was corrected by the end of the whole thing. Evil Cap, aka Hydra Supreme, was a brainwashed version of the Star-Spangled Avenger.
Eventually, the real Cap escaped from the Cosmic Cube that created the problem in the first place. It was certainly shocking to witness Captain America reveal "the truth" but once that shock wore off, there was little substance to it.
4 CIVIL WAR II: Captain Marvel Vs Iron Man
A huge part of what made the first Civil War story work was the breakdown of the relationship between Iron Man and Captain America. Their friendship saw them through some of the hardest moments in the history of Marvel Comics, so watching it fall apart was powerful.
As great a character as Captain Marvel is, she and Iron Man do not have that kind of bond. Civil War II lacked the emotional component its predecessor had, something it tried to make up for via the deaths of several prominent heroes.
3 SECRET EMPIRE: Next Step After Civil War II
One of the biggest sins of the Secret Empire was that it fulfilled one of the prophecies of Civil War II. Ulysses had a vision of Miles Morales killing Captain America, or at the very least beating him to a pulp.
As it turned out, that vision was of Miles beating up Hydra Supreme, which was a fun moment for everyone involved. The problem was it proved Iron Man's point about Ulysses in the first place, that the visions were suspect at best. It minimized the deaths of heroes like the Hulk.
2 CIVIL WAR II: Bad Follow Up
The first Civil War was a story that asked some hard questions about being a superhero and how they fit into society. Civil War II, on the other hand, did not. It was a bland follow up to one of Marvel's seminal events, one published purely to capitalize on the popularity of the MCU film Captain America: Civil War. The unfortunate reality was that it did not live up to the high watermark set by its predecessor.
1 SECRET EMPIRE: Controversy
While it did not have a successor to fall short of, Secret Empire did have its own inherent flaws. There was quite a bit of controversy surrounding the Captain America twist as a character created by two Jewish men was revealed to essentially be a Nazi. Additionally, there was a cover that featured Magneto with members of Hydra, the incorrect implication being that he was allied with them. Magneto's backstory leans heavily on him being a Holocaust survivor that hates Nazis. These missteps certainly colored people's opinions of the overall story.