I played City of Heroes/Villains and Champions Online too, and I still think DC Universe Online is the best one. True, the chat-system was pretty bad at launch, but it's improved. It's not perfect, but they are improving it.
My biggest issue with City of... is the lack of variation. I first went into an office to fight some enemies. Then I was supposed to go to a warehouse and fight different enemies, and yet the warehouse was literally right next door to the office and looked identical on the inside. Even the enemies were identical. It got a bit better with City of Villains, though. Now you had
two different types of enemies (humans and snakes). Yay!!!
I think there were small robots in one, but they were just a small part, sadly.
Oh, and don't forget kill-stealers. I was beating up a difficult enemy in Villains and had almost killed him, then all of a sudden a high-level idiot ran up to it and killed it. I told him what I meant about it (and reported him), but he said I got the loot, so what did I complain about?
As for Champions, it wasn't bad once you got used to the ugly graphics. But I thought it was pretty boring and lacked a story. What it didn't lack was players camping around quest items, trying to pick them up when they respawned. When you have six or seven people waiting for one quest item (and you need five of them), you see a problem. The idiotic instances didn't help, either. MMO's are supposed to be massive (it's in the name;
massive multiplayer online), and a game with lots of small instances or zones doesn't give me that feeling. I need a big, open world like in World of Warcraft, Lord of the Rings Online or DC Universe Online.