@Giannysmag I was doing my tier list to see where I ranked the verse so I could see why I might disagree with your top ten to top 15 for the verse. And I realized it really comes down to three big things as to why I think he doesn't get to crack top 20.
Raw Stats: While he might be a physical monster Mahito at the height of his strength I do not believe ever reaches that space that the top tiers of the verse exist within. His big issue is that the Yuji he fought is weaker than the Yuji that most of the top tiers scale above and at best he has a 2x stat difference in terms of durability from the Yuji he fought. Unless we're going to argue that Yuji doesn't get that much tougher from this point in the series, which then leads into the issue that if that's true we do have enough characters comparable of above Yuji's strength who'd still keep Mahito out of the tops of the verse. And that's only in his best state which Mahito wouldn't always be in due to the restrictions that come with IBDK (the loss of his ability to modify his own body) as if he's not tough enough or strong enough anyway, he's better off messing with his form to increase versatility. Endurance wise, when Mahito is really taking damage he's not a special case as its only a few strikes from Yuji which puts him low in terms of soul power. Speedwise, even ignoring Cursed Naoya who instantly keeps him from like Top 20, there's little to believe in that he's even faster than the likes of normal Naoya and Naobito which are characters which Jogo and Choso end up comparable to (though that also ignores how Projection Sorcerer is difficult to deal with for more than speed reasons).
Counter Play: Simple Domain negates his CT. As established with Mechimaru, any simple domain user would be able to hurt Mahito if they entered his physical range and most of the top tiers either have a simple domain and those not even in the top tiers (Kusakabe) also got it going on, something with soul damage (Maki and Toji) or a domain expansion (which would be more polished than his) but that'll be dived into last. Hell, Mahito doesn't appear to know Domain Amplification like Hanami and Jogo do which would make it hard for him to even handle those two. He'd end up being a Higuruma victim (and Higuruma is really just hanging out near the bottom of top 20).
Domain Expansion: Mahito has a great domain expansion, however, most characters in the verse with Domain Expansions should have theirs more polished than his. Yuta, Kenjaku, Hakari, and Higuruma are obvious choices. But even the likes of Ryu and Yoruzu and Uro should have more polished domains as longer lived sorcerer's and each themselves worthy of a special grade status (maybe not Uro). And losing those domain clashes is death for him, which he'd probably lose quickly due to his relative inexpereince being a hamper even against his insane talent.
Overall, while Mahito could've become a true top 10, hell Top 5 contender for the verse he got taken out before he could truly climb to those heights.