DC has a Bat infestation problem. There are too many books focusing on too few characters and settings. The reality of it isn't as bad as the marketing image that they're projecting. They've got some decently diverse books, but they seem to get brushed aside and want to constantly shove the bat stuff and Superman in your face all the time.
Don't get me wrong, I like Batman. I'm not a hater of him or the Bat family, but there is too much of a focus on him throughout the publications. They do print other things, but according to how they market themselves pretty much the only real alternative is Superman and every other minor book is almost universally connected to Batman or Superman on a regular basis.
I know Marvel has it's 'flagship' books too, but overall their other stuff is more diverse and has a greater tonal spectrum. They do touch on each other, but are much more loosely tied and many of the books are able to do their own thing without feeling like an extension of the big books as much.
I think it's that DC removes the sense of space and distance between the characters and makes it all feel oddly local, almost as if it's all happening within the same city even though I know it's not, but it does often feel that way.
Marvel's writing is better about giving a sense of distance between the characters and their world. It's all still connected, but not so much that it's as if it's all happening within a very small area I guess. They have a much wider tone spectrum in their books and characters than DC does these days. They need to start pushing some of the other stuff they print and cut back on the Bat family and even Superman a little. Not cancel the books or anything, but put some more effort and focus on separating their other characters from those franchises a bit more and give them their own space to live in.
They do a good job of it sometimes in their non-flagship franchises, but they don't market it well enough and always end up dragging things back to Superman or Batman characters. I think people are getting kind of sick of it.
That, and their tone is getting kind of stagnant. They're still a bit stuck in their 90s Goth phase where everything is serious and gritty. It's being reflected in their film franchises and people are outright telling them to take some advice from their own character now and stop being so depressingly serious.
Man of Steel was literally designed to suck the joy and color from Superman for some strange reason. I get that tone works for Batman, but DC doesn't seem to get that it doesn't necessarily fit for every other character in their roster. I think Will Smith as Deadshot could be inspired casting, but only if they let him actually be the fun Will Smith and not the depressing one from his drama work.