One i can think of is the Runaways.
EXILES - Though, after New Exiles, it was more of a Mercy Killing. However it was a gratuitous mercy killing, that was so brutal, that even though it came back from the dead a few years later, and was written by Jeff Parker and was good! The taint of death made people think it was a zombie. So it was cancelled again, even though it started being good again! Thank you CC for more than a decade of awesome Uncanny, but why CC, why vomit on the cake that was Exiles, and then throw it out the window like a brick covered in tar. WHY!
" @jloneblackheart said:" Guardians of the Galaxy "Oh yeah. that was a great book. Then again all of Comic Marvel was amazing. TI ruined everything. "
Irredeemable Ant-Man comes to mind. That was just a fun series that was killed before its time. I also think Immortal Iron Fist was pretty great for a while, and would have eventually become great once more if it had survived long enough.
Personally, I'm glad they canceled Runaways. I love the title, and it is still one of my favorites books, but the quality had dropped so far by the end that the best thing they could have done was to cancel it. I'd rather it be canceled than continue to be terrible.
It's too bad Agents of Atlas didn't last longer. I really liked the team and the book had a lot of promise. I also miss Avengers Initiative. Avengers Academy is good, but I rather have seen Initiative continued. Unfortunately, I doubt the characters from Agents of Atlas and Initiative will show up anywhere anytime soon.
I also have a certain nostalgic fondness for Battle Chasers. It wasn't actually canceled, though. Instead, the delays kept getting longer and longer until Joe Madureira just stopped making it. It was a fun book with good art and there isn't really anything like to today.