I'd have to say Daedric Lords hands down. The Aedra are weaker because they took part in creation. Daedra never had to give up their up powers to make the world so they stayed strong
http://www.imperial-library.info/book_daedra/
Under Creation Myth, 5th & 6th paragraphs talks about that. So you're right, the et-Ada were weak after creating a world (after being persuaded by Lorkhan) and there were other daedra like
Y'ffre but he transformed into Ehlnofey and the only ones that were left were the eight we know today. This project of creating a world wasn't enticing to the other et-Ada, and so they became the Daedra. Ya know, I guess that makes sense in a way as they are not our ancestors since they didn't take part in creating the world in which all the denizens of Nirn now live. The Aedra, in a sense, are our oldest ancestors because they created the world Nirn that everybody lives on. I'm going off on a tangent here, though. But that sounds correct, right?
So the daedra are stronger since their fellow et-Ada who were weakened by creation and became the Aedra.
If the process of creation harms et-Ada (daedra/aedra) then shouldn't the Aedra creating more things after wards still harm them further yet? And in that sense, wouldn't they become so weak from creating that they'd eventually die? And what types of things are we talking about in the sense of creation? A grain of sand? A flower? A rock? A person? A land? A race? A world? A star? Something not material or physical like an idea or law or concept? People say "creation" but what exactly are they creating that makes the Aedra weaker and weaker? Or does their weakness simply reach a plateau?