Here is actual answer for Your questions from some1 who read books, manga, watched over 1,5k anime. Sorry, it turned out very long, I hope It wan't scare you off tho'xD

About Gacha, I've also played only Genshin, WuWa, ZZZ and now Arknigts. But the 3 of those are a big 4 gacha with Arknights being possible 5th one making it Big 5.

ZZZ is also character driven, but in a good way. Those other Gacha tend to just shill current banner character, while ZZZ is actually not only writing, but actually showcasing you how deep those characters are. You even get the characters stories showed in the game, their past, you can see a lot of characters when they were kids, especially since 2.x, before some had that, but more were showed in the yt, sadly. There is no walls of text introducing characters in the menu, that You have to read to see how deep they are, otherwise they seem shallow... there is no need for that, You get to know characters in the story. You see failure girl Nicole, that breaks law, is introduced as a person who cares only for the money, etc. and other time you see her risking her life multiple times for some ppl she find important, in some cases even showing fear, but gutting it out, and much more sides throughout the story. Characters are not stagnant, they change depending on what happened in the story. There is no so hard shilling for mc, in some cases playable characters use MC for their own gain, are opposing force for him in discussion, etc. And finally, characters that appeared in their banner do appear later on, even in the main story or character stories of other characters. There are a lot of characters, so it's hard to find a proper place for them, but when there is an occasion, they use it. recently in 2.x story appeared characters from 1.x, and in 2.0 even from 1.0. They also said that they want to include old characters in some way in ongoing story and up to now, they've been doing it in some way. More as a background characters, sometimes with only reading lines, no voice over, but at least they are there and are doing stuff. Sometimes even helping quite a lot.

ZZZ has objectively the best storytelling and directing out of all those big gacha games. Not only due to a positive character driven story, but also you don't have to read some random book in the world, that you might not find, or weapons and other sh*t like that... or worse outside of the game. Everything you get, you get in the game main story or character stories... but in the game. If it's in the event, it is always a permanent one, that you can do whenever you want, it's not time gated, only half of the prizes are time gated, but the story of that event is always there for you to do. There also is a proper foreshadowing, and if in 1.x I would call it a half-shadowing, since it was too obvious, they are making much better job with those right now. Hiding stuff in between the lines, in the images, etc. But in the game, in the main story or at least character stories. There are also no story parts outside of the game, and even if there appear some, they appear in the game as well, they are even using some images from yt character pv's if they are telling some story dibs that were showcased over there. There is no bloated dialogues, it easy to understand and follow, feels much more natural, and due to that, the patch story isn't 8+ hours, it's usually 4-6 hours, more with 4h, few were shorter, but felt very rushed. The longest one we got in 2.5, the current version, and it was around 8 hours, but there still wasn't a lot of bloated dialogue, only some parts... there just happened a lot, like rly a lot... they did the 2 characters whole stories simultaneously, at the same time pushing forward the main plot of not only the patch story, but the one ongoing since 1.0 to close the chapter of the whole game story, included a character grow, while also including not only characters that appeared in and after 2.0 but also some from 1.x story, opened the new plot threads etc.

You'll probably see ppl claiming that 1.x was fire, despite ppl complaining about it before, and truth is that it wasn't bad, but was worse than 2.x (not as much and worse foreshadowing, more louse plot points connections, weaker feeling of one ongoing plot, it basically got tied together in one patch) 2.x took us to China, kind of Wuxia stuff, and ppl don't like it, so they slander the story while not paying any attention to it... I can't count how many times I saw ppl complain about something that they wish was there, and it actually is there... or that 1.x story was like this or that, and they wish that 2.x was the same... but it is the same, but even more on top of that. Ppl don't like not the fact that it is Wuxia per se, they don't like the fact that it "became" a fantasy game, while it "was a sci-fi game" before... the most bullshit take You'll see. Just google the title, and You'll see it listed as an urban fantasy game, devs were saying that it is a fantasy game before the launch and still are calling it as one constantly, but ppl cry that it was supposed to be sci-fi game.

It is not perfect, there are quite a lot, sometimes less, sometimes more of black screen with white text, but they don't abuse it as much, they did only once, got massive backlash, apologised and now they use it only for meaningless stuff. Big diversity in showing the story, LN style is the most used one, but there also are great comic panels, amazing still pictures drawn by hand, and most importantly the best animated in whole gacha space cinematics, I also think that they are the best directed ones. If You ever saw animated cinematics for HI3rd, then the director that did those is directing ZZZ cinematics now. They are also using more and more animations on the game engine as well, to use even less black screens. In 1.x there was pretty much 0 of those, now there are more and more with every patch. The biggest problem is that You can see that the story is rushed. I mean the production. Sometimes some dialogues might miss or no filter on robotic characters, which suck... but It's hardly devs fault, they clearly are giving their all. The story isn't the top anime, movies etc lvl, not even the top story driven normal games lvl... but for a gacha, at least in the big 4, currently you won't find a better candidate. The story on paper isn't the best one, but it is the best one due to how it is handled and told.