One of the most common jokes among fans of comic book films is that Marvel is who you go to if you want something bright, colorful, humorous, and occasionally even a bit silly, whereas DC is who you go to if you want something dark, brooding, grim, and quote unquote "mature."
This is why it may surprise some to know that DC do not take the extra step to give their films an R-rating nearly as often as Marvel does. Whereas Marvel have put out a total of thirteen R-rated films over the years (all of which are live-action), DC have only released eight, half of which are animated features.
As with most things, these films drastically differ in quality and the R-rating often plays a part in this. Some use the rating to their advantage in a way that lends itself to the story and subject matter on display, whereas a couple of others get just a bit too gimmicky with it. Additionally, the MPAA aside, some of these films are simply that much more entertaining to watch than the others.