Maybe it's because it's supposed to be obvious and maybe I just wanna talk about it because it's my favorite quirk In the series, not because of the power but because of what it represents but I genuinely do feel like One for All is the most beautiful power and symbol in MHA.
It's a power created by human connection, and whenever it's passed on, it's basically telling the next user that, "I know you'll be able to carry on our hopes and our dreams, even after we're long gone." When you inherit OFA, you don't just inherit it's power but also the courage it comes with having it, because now you're not just living for yourself anymore, but for everyone.
While most quirks represent the user themselves, OFA represents the selflessness the users had to give parts of themselves away for the sake of those in need, for the sake of someone's future.
One for All proves to all those who inherit it, and all those around it that human goodness can accumulate into something beautiful.
One for All isn't just inherited power, or even ultimate power.
It's inherited hope.
(I'm sorry if it's sounds like a jumbled mess, the thought just wouldn't get out of my head and its something I've been wanting to express and talk about for a while now.)