Depends. I feel Geoff Johns, Scott Snyder, BMB, Hickman, and sometimes Waid feel more mature. But there is some Marvel and DC oriented towards children Lil' Gotham, Adventures of Superman, Legends of the Dark Knight, Nova, the comics based off of TV shows, Hawkeye are all good examples of comics that children could get into.
However, kids should avoid Image comics... at a very far distance. Well, except maybe Super Dinosaur.
All this being said, I think ratings are sufficient and should be displayed somehow. I do know that some specify that they are for MATURE READERS, while others can be judged just by looking at the cover (although the baby variants and future LEGO variants are/will be misleading).
Since when is Legends of the Dark Knight a kids book? o.O I recall a genetic abomination killing its creator and than being kept as an exhibit in the Batcave...
When it's a fight to the death, Deadpool will ALWAYS win, but since this is to a knockout, I'd hand it to Bats for everything the author listed, except for fighting skill where I think Wade's more adept, since most of his style is "as it goes along" per-se, and unpredictable in that manner.