Superheroes are the best kind of silly. They promise you a fun action filled adventure and lovable characters of all kinds of variety. They are easily accessible (for the most part) and speak to a huge audience. And with that they tell great stories about all kinds of subjects. It is also super rewarding to keep up with comics. The deeper you get into it, the more characters you'll recognize in huge event comics and the greater the payoff is, when a long story arc comes to a conclusion. But you can still just pick up any cool comic and look at the amazing art and have a good time.
I think being accessible is something severely underestimated in art in general. If you can sell me a premise as silly as Superheroes in Spandex flying around the world to save people, you must be a god artist in my book ^^
I myself am a huge Green Lantern Fan and LOVE the stories, themes and characters they explore with it. The new Earth Lantern being a woman with phobias, who struggles with the reasons she has been chosen gives great opportunity to talk about mental health. I also love how Geoff Johns introduced other colors to the mix, so you can have widely different ideologies and emotions approaching the crisis of the day, making the whole "good vs. evil" thing a lot more complex.
I also quite enjoy a lot of DC characters and how they interact with each other in assemble comics. As @jpnakashima said the heroes themselves stand have often interesting and even allegorical backgrounds and it's never ending fun for me to so many different people clash over essentially wanting to do the same (save people).
I still have a lot of things that annoy me with superhero comics though (which doesn't stop me from expanding my collection).
We have cool legacy characters? Oh no! People might not recognize them! Reboot!
I want another Spiderman! We already got 50?! Well, time travel or parallel universe, d'uh!
Character dead? Nah, bro, just a prank.
Buy this comic from a different hero, if you want to know what happens to your favorite one!
This was a really nice conclusion and would be the best ending to the series ever! But nah, of course not.
And so on...
Still, I can get behind all this for the amazing stories I have gotten. I just wished the industry wasn't as big in movies right now. It's getting exhausting.