Deadpool is not grounded in his motivation. You just have to look at what makes either character insane. Joker wants to get Batman to kill him. That's a pretty grounded motivation that is completely feasible. Whereas Deadpool wants to die and can't. So he'll try repeatedly over and over and over to get whoever he can to do it and kill them in the process. This has nothing to do with how bad either of them are or the type of insanity you think they have. Remember that time Deadpool lost his shit and killed Marvel? At least as sinister as Joker that story. But he's more insane because he's completely unpredictable whereas you know what Joker's intentions are at all times. He could be on X-Men's side and as they start losing he might immediately join the side of their adversary. Then might later stab them in the back. I could never see Joker as being so random.
Deadpool is not grounded in his motivation. You just have to look at what makes either character insane. Joker wants to get Batman to kill him. That's a pretty grounded motivation that is completely feasible. Whereas Deadpool wants to die and can't. So he'll try repeatedly over and over and over to get whoever he can to do it and kill them in the process. This has nothing to do with how bad either of them are or the type of insanity you think they have. Remember that time Deadpool lost his shit and killed Marvel? At least as sinister as Joker that story. But he's more insane because he's completely unpredictable whereas you know what Joker's intentions are at all times. He could be on X-Men's side and as they start losing he might immediately join the side of their adversary. Then might later stab them in the back. I could never see Joker as being so random.