Well Hobgoblin suffers due to the fact that Stern didn't get to out his ID before leaving the book, the editors didn't believe it could be Kingsley so we got the Ned Leeds junk. Then the new 90's Hobgoblin quickly became a joke until Stern returned for Hobgoblin Lives.
Then Osborn was brought back..............
Alpha Flight, such a ruined team concept.....
Monica Rambeau, he was depowered and left the Avengers to recover. Now ever since then she was marginalized and left as the "go to" to get approval to use the Captain Marvel name until Carol claimed it.
Richard Rider: I blame SJW for what has happened to him. The PTSD he currently has is understandable but he could still be so much better.
Vision and the Scarlet Witch: we can thank Byrne for Vision becoming a toaster, or should I say Data from TNG for some time, and for Wanda going crazy.
Other characters that have been screwed up:
Spider-Man: One More Day/One Moment in Time/Mephisto Mindwipe
THOR: since before Foster-THOR, THOR has been getting screwed up. Then for years we get emasculated THOR whining about his hammer while being drunk. Now he is KING (Again), and has to deal with an insane/corrupted Don Blake who I thought was written out for good by previous writers in the first place. I await the next Ragnarok-reboot of Asgard.
Iron Man: TWo times Tony was corrupted/turned evil and it was ended by his being killed and restored via Deuz Ex Machina. Then we get the gow awful story of Tony thinking he is a robot and Arno taking over as IM 2020, plus the whole TONY IS ADOPTED NONSENSE. Awaiting the great cosmic revelation that Tony's timeline has been tampered with by Kang.....
Ghost Rider: Dan Ketch is marginalized and tossed aside. Robbie Reyes is an SJW JOKE, and Blaze is being badly written as King of Hell. The latest series was cancelled after about 8 issues, just like when we had SJW-female Ghost Rider whose story was finished in Thunderbolts.
Make up your minds Marvel, is Ketch a Rider or not? is Blaze damned to hell or not?
Phantom Rider: Carter and Lincoln's ghosts are cast into the ether again, Hamilton Slade is dead and his daughter who is full of hate was corrupted by Lincoln into a new evil Rider. When will the new hero version of the Rider arise to set things right?
Captain Mar-Vell: yes here I go again. Bring him back, there are many stories to tell about the hero/legend who really DID die, unlike others who have returned, and who the universe and its peoples would feel about such a return?
hero? savior? pariah? messiah? destroyer?
We got a glimpse of such reactions when SKRULL-VELL (ARGH!) was running around. We got another glimpse when the Phoenix briefly revived Mar-Vell.
Now bring him back for real this time! I highly doubt Marvel needs Starlin's blessing on the matter.