A sizable part of my aversion to a lot of anime is probably related to the fact that the majority of titles in the past couple decades are centered on children or teens, and by and large cater to that demographic. That in and of itself is fine, and some of the best anime explore the important themes of that stage of life, but the portrayals of kids in most shows are usually reductive, unrealistic, immature, shallow, or just plain stupid... and while most kids undoubtedly aren't quite ready to forge their own way in the world, I think children are more complex and often more savvy than they're popularly given credit for.
Having said that, what are some shows that do a good job of showcasing the depth of their young cast? Two have stood out to me:
Hourou_Musuko / Wandering Son. If this series can't humanize the struggle of growing up trans to you, you're dead inside. It's only 12 episodes if you watch the two specials (necessary to get the full story, they were edited together into one of the main episodes), but pretty much every one gave me so much pause to reflect on my own childhood.
Dennou Coil / Coil - A Circle of Children is the best depiction of children I've seen in anime. Creator and director Mitsuo Iso's respect for the characters, despite their age, is impressive, and I felt it captured the perspective of life at that age - the intra-group politics, the uncertainty, the courage, the discovery, the disappointments - very well. I think its strengths elevate what could have otherwise been a pretty straightforward adventure story with an interesting premise into something rather special.