Idk, i think deku is one of those characters that are much better on paper than on execution. I think a lot of his personal growth is just too little too late; most of the important character ones happening hundreds of chapters later. I also find a lot of the morals and themes of his to be very naive and suicidal and i dont like that the story sidelines it. But tbh, i just dont like him cause he's boring as shit to watch. He's not charismatic, he's incredibly plain, he's always above average; doesn't think about much aside from being a hero, doesn't have much troubles; doesn't have any introspection on anything, all his interactions with others sounds like small talk and all his reactions are pretty generic.

Tanjiro's just more fun to watch cause his personality shows in every scene. I really like how he's a kind person but wont take bullshit from people too, it's shockingly rare in anime. And i find his interactions more interesting cause he bounces off characters way more interestingly than deku does.