To explain why this is, I think that you will agree that on the rare occasions in which John isn't letting his laziness, arrogance and cruelty warp his thinking, he's capable of acts of great insight and cleverness. While he's usually clueless because he doesn't want to actually live in the real world and sort of hates to think about what's going on around him because he fears being the bad guy, when he does get unwedged, he can be pretty sharp. The same thing seems to apply to Michael (and April) because he too can really do some clever things when he's not copying Elly by feeling sorry for himself, obsessing over how everyone seems to hate the idea of his being happy too or wishing for a miracle that would get people to like him and really want him around.
I think that it's also safe to say that while Liz shares with John the tendency to see people not as they are but as she would like them to be, she shares with Elly having a baked potato where a brain ought to be. Elly tries to bargain with dogs and Liz panics at the horrible display of preschoolers making up words so we ain't exactly dealing with intellectual giants here. Liz thus loses out because she combines John's lack of curiosity and smug belief that the world has to adapt to her whims with Elly's poor impulse control and lack of brain power. This isn't to say that Mike is much better off. His horrible need to finally have Elly admit that he did her a favour making her a mother makes him as dysfunctional as his idiot sister and as in need of a stern minder as she is.