1.) Midoriya: With one for all, he has the power to one hit even hero killers like Muscular.
2.) Todoroki: He's capable of great feats with his freezing quirk alone, there is no telling how powerful he is with both his quirks.
3.) Momo: Her creation quirk is little that of a god, she can create something from nothing by only knowing how it's made. With her quirk and her high than average intelligence, she can think her way out of any situation.
4.) Bakugo: Though his quirk isn't that powerful, Bakugo's fighting style allows him to use his quirk to it's current max with little effort.
5.) Uraraka: With her Zero Gravity quirk, she threw a ball into space where it will travel infinitely. If she were to really get angry, she could possibly throw something at whoever she is angry at that would likely go through their body. Her quirk is powerful indeedm, the only reason she is not number one is because we have yet to see the true extent of her quirk.