User blog comment:B214/Shin DxD 1 discussion/@comment-3965848-20180903064427/@comment-31137559-20180908063509

One, this isn't Rakudai Kishi.

Two, a Rating Game isn't a one-on-one battle.

Three, no one is the favorite to win at this moment(unless you're talking in context of who the fandom favors instead of who's more favored in the series itself)

As powerful as Issei is, he just isn't that good a king. Yes he has won all but one of his matches and he's a natural leader. But still he's very inexperienced as a king. His team can be one of the most powerful and he may have won all of his matches, but Rating Games are more than just an absolute showing of power which most people tend not to believe.