Other than the continuous blabbering, I thought that all three main arcs are really, really good.
THe Loufu is constantly criticized, but I feel like part of it is due to the way they split the whole story in multiple patches with no reasons at all. I enjoyed the scene-to-scene story, all in all. It's probably the one that I like less as well, but the characters were all so good in all the interactions. The luck of having Jing Yuan, Dan Hang, Welt and the such interacting is huge for me.
Belobog is reallly good because it has the best pacing and the most straightforward story, but the final boss of 2.2 is miles and miles ahead in terms of depth compared to Cocolia, it's like night and day. Penacony employed way too much dialogue with so many unnecessary concepts that give us a resemblance of depth and lore, but the way it's presented discourage the player to go and actually interact with it. If they need to talk this much, we need more cutscenes at least.
I do think Star Rail will improve in the future on this regard, though.