For me, there’s sort of two.
The first one is I really wish we got more of Cullen Bunn’s run on the Agent Venom series. It wasn’t quite as good as Remender’s previous run, but it still had a lot of great moments and was clearly building to something bigger. I actually got to ask him about it when he did an AMA on Reddit. In a farewell letter he mentioned what he “…had in mind for The Descent, his plans for Toxin and Mania, the emergence of an all new Anti-Venom…” and “…the War of the Symbiote.”
I asked him if he could expand on that and his answer was “There were many things I had in mind for VENOM, but I had to wrap them all up rather quickly. For instance… – There was to be a lot more with Mania. I really wanted to show Flash trying to be a father figure for Andi and Venom trying to be a mentor for Mania. I also had a story in mind in which Toxin would try to take Mania under his wing. – The Descent was, when originally conceived, going to be a big war in Hell kind of story, with Venom, Mania, Toxin, and the Circle of Four characters almost like a group of soldiers behind enemy lines. – The new Anti-Venom was something I was pretty excited about. When Flash took over as Venom, there was a mention that he was not the first candidate for the symbiote… that there was another host before him. I can’t remember exactly at this point, but it was almost a throw away line. My plan was to introduce that previous candidate as another symbiote-powered soldier who wanted to destroy Venom. He would become the new anti-venom. --The War of the Symbiote was supposed to be come an arc or two after the Mania arc. Basically, everyone who had ever worn the symbiote would be drawn to it (kind of a pheromone incident) and go to war to get it back. Spider-Man (then Spider-Ock), Scorpion, Eddie Brock, Flash, and anyone else. The symbiote would be jumping from person to person during this “war” and in this story Flash would have finally learned Spider-Man’s identity.”
So yeah, that left me even more blue ballsed…
I also wish we could have seen Millar stick around for more Ultimate Universe stuff, but that’s because I’m both a Millar and a UU fanboy. I got plenty of that already, so I can’t really complain.