It depends for me. I really hate media where the characters are meant to be teens, but act like fully realized adults. Where it feels like the characters are only a certain age to pander to their target audience. Harry Potter is actually a good example, I find Harry very boring and I hate how he acts like a grown ass dude in the last couple of movies, whilst he acted like a very boring child in the first couple ones. Only exception to that rule are Jotaro Kujo and Giorno Giovanna from JJBA. Jotaro is a 17 year old that wants to appear as mature as possible, with Giorno it's pretty well explained why he acts the way he does at 15. And both showed childlike tendencies at times
I love Chainsaw Man because Denji acts like a 16 year old boy in rather special circumstances. He is very much like I was at his age, we see him develop and become an adult. The other characters treat him like a 16 year old, for the better or worse
Similiarly, Evangelion is wonderful because it shows how awkward and uncomfortable it is being 14. You are no longer a young child, you are not an adult, your body does weird shit, your brain goes places that bring you discomfort and you can't do anything about it. It completes the message and the narrative
Peter Parker, Monkey D. Luffy, Edward Elric, Mob are all teenage MCs I really enjoy reading about for similar reasons. One of my favorite MCs ever, that is rather unknown, is Shizuka from Takopi's Original Sin. She's like 10 or something but she manages to be really interesting and reminds me very much of myself at this age. You should read that manga, it's very short, you can read through it in like 2-3 hours
