if you don't know Madoka watch the anime Mahou Shoujo Madoka Magica

he is immortal...........and his Death Predation magic which he release with or without his consciousness can kill anything in this world........which makes him undefeated .................he he he

KEISUKE_URAHARA, Madoka is god, nothing can kill her Zeref would not do anything to Madoka at all she is the law of cycles. Nothing can touch Madoka she is the power of every single universe, multiverse, xenoverse, omniverse, and etc combined. She could just erase all of them from existence, or just simply use universe level of attacks and strike a googolplex amount pink arrows that is more than powerful enough to wipe out every universe in a single blow

and also Ultimate Madoka is a conceptual being where even somehow you went back in time before she became powerful to kill her. Ultimate Madoka will not be affected, and also she can see everything from every timeline, past, present, future, and alternate timelines too.

even though nothing could touch madoka. Madoka herself can still touch everyone. and the only people who can touch her are people who are best friends with Madoka and whoever Madoka is loved by when not fighting. zeref will not be able to kill Madoka because God's immortality is a Googolplex years greater than even Thanos and Goku together. Zeref is just simple immortality

the only God on par with Madoka is the Christian God Jesus

Madoka easily solos everyone else in this list by just simply pinky stomping them.

also Watch the Madoka Magica anime if you don't want any spoilers of Madoka Kaname it is 12 episodes it has 2 movie recaps and 3 movie which is a direct sequel and one side story anime based on the Madoka Magica Side Mobile app game Magia Record and its 13 episodes.

Acnologia would win. It has been proven that he is more powerful than Zeref but Zeref is immortal. Though Zeref WAS trying to kill Acnologia and could not so... Idk about that Madoka girl or whatever