Yea, the difference is other MCs are "nice" but it never feels like those characters are actually nice people; frequently it's a performative "nice" where you can tell the characters, or maybe the author too, have their motives in completely wrong places. Many times its a spiteful, even malicious-compliance sort of deal. To put it harshly, an incel kind of "nice".
Meanwhile Sora here has felt like an actually nice person. You get the feeling you would actually want to be friends with someone like him IRL unlike other "nice" MCs.