They have not much feats unfortunately. There is room for others where Sakura Tsunade Temari etc stand. Noone should be mad.
Karin is cool, Kushina literally got a bijuu extracted and got up still held out and did work for a decent time after AND she just delivered a child. Need anyone say more
Kishi had a set of amazing women in the series, Shame he had to keep them in the shadow of the men.
To call them the most powerful would be in denial of their lack of feats. Them having a technique that can take out large targets doesn't make them the strongest to me.