User blog comment:Bennia Lover/Other media discussion/@comment-162.252.126.39-20171010201416/@comment-3435913-20171010223542

Issei hands down. Considering Great Red and Ophis are the two most powerful beings in his universe, there is really no contest. We could assume Shido at full strength could be equivilent of a god, and there are certain angels that give him an edge like Zaphkiel or Michael. Basara is very powerful, and banishing shift is a trump card with a very good advantage over most opponents. But, Issei still has Boost, which he can push to infinity and thus a battle that doesn't prolong is an easier win.

In a long battle of attrition, Issei could possibly burn himself out and hit a wall of endurance. If that were to happen and no breast are easily availible, then I would favour Shido who has more options in his abilities to avoid or overpower the other two when smashing unstoppable forces together is no longer viable.