That was my feeling with the manga too: Good and different, with little enough missing that you could easily switch between the two. I think I actually preferred the anime a little bit because of the Miyazakian visuals. At this point in my life, however, I need relaxation and good cheer so I've been doing more lighthearted stuff and I've set aside Made in Abyss for now.
As far as K-On! goes...
I just have an aversion to character design that comes from moe, rather than letting moe come from character design. It's like... Rei Ayanami was original and interesting the first time you see her, but then EVERY anime HAD to have an Ayanami style character "Because she's great" - without regard to what made her great, the fact that she was unique at the time. It's as though that big tank of clones had a dimensional rupture right in the middle, spilling her all across anime-dom.
That's my main problem with K-On!, Girls Und Panzer, Love Hina, and a bunch of other anime that I've deleted over the years and frankly forgotten the names of. It seems like they started writing with, "Well, we need a genki girl, we need a sheep, we need an Ayanami, we need a nadeshiko, we need a geeky one who's a bit genre savvy..." instead of starting with a story and allowing the characters to grow from there.
Hell, I didn't try Haruhi for close to ten years because of that obvious moe-factor in the designs of the main three females, and really only gave the anime a chance because of the novels.
But hey, that's MY personal feelings on the matter, and I can't help what I dislike, just as MadCap has every right to dislike KyoAni.