I can’t speak for anybody else, but I consider Anchor’s grading to be a very good start, especially to give me some ideas about heroes before I max them.
Not the final answer, but usually pretty good. In addition, over half of it is strictly factual, like mana speed and tile damage, all neatly compiled. Other parts are opinions, including final grades, but they are opinions from a group that has played twice as long as I have, so I value the opinions.
In the case of Chao, several equally experienced players have expressed that Chao is better than a C hero, and their reasons make sense to me, in this topic and elsewhere: