Mini-rant first to clear things up:
The US has too much of a mentality that animated shows are just mindless comedies for young kids. Japanese animation, often called anime after the art style of the same name (really people need to stop using the term and grouping it like that, animation is animation), is different in that Japan doesn't have that mentality. They put a lot of work into their animated shows. And it's their medium of choice, often made to a higher level of quality than the majority of their live action shows. Because they don't have the "comedies for kids" mentality that the US has, and that they focus more on animation than live action, Japan has a large number of animated shows that are meant to appeal to all sorts of audiences. Some are for kids, yes, but others are targeted at teens, and others to adults, and others are for generally older than kids audiences. And because they do ti so much more, there's a wide variety of stories. Just like in the US, the vast majority of it is not going to appeal in the slightest to any individual person (so no more of that anime is so amazing talk). Since they have the larger volume, that means there will be more choices of shows that any given person will like. That is why when you look to Japanese animation there's usually something there for everyone.
That being said, I do like some of the animated comedy shows meant for older viewers in the US. Simpsons, Family Guy, South Park, Futurama. But they're never something you sit and think "damn, I really want to watch the whole series again." I do have soft spot too for Danny Phantom and Invader Zim. Other than that the only purely American animated shows I like are Avatar the Last Airbender and its sequel series Korra. They stand out as the most intricate and detailed animated shows in the US that's not a dub of a Japanese show. I think more shows like it should be made following a similar model taking inspiration to things Japan is doing, but not necessarily having to use the anime artstyle. You can make a good show without it looking like it was made in Japan.
For Japanese animation, I haven't actually found many that I really, truly love enough to say I like it. But the first four seasons of Digimon I'd say counts. Those were amazing. Each one felt different and had its own strengths and flaws and I don't feel right saying one is better than the other. But definitely I didn't like any of the seasons after that. And I'm incredibly disappointed that the Adventure sequel is going to be a series of movies instead of a show.