Okay so I wanted to point this out; I do not care if Goku is stronger or weaker than Superman, I just wanted to throw in my two cents about the debate. But I'm not saying that Superman is the strongest character in all of fiction.

Disclaimer: I am assuming that the claims of infinite power within my argument are 100% legit. I am not debating whether or not these characters are 'higher dimensional' or 'multiverse tier' in power; I am considering that they are simply because it is relevant to their concept. I will not consider counterarguments based on assumptions; because I am aware that I am making some assumptions.

The two strongest characters in fiction; Dan Hibiki and Tsuyu Asui… nah just kidding.

It's; Horakthy, the Creator God of Light from Yugioh and The-One-Above-All from Marvel.

It's GOD.

Starting with Hora; this is her ingame ability: 'This card's Special Summon cannot be negated. The player that Special Summons this card WINS THE DUEL.'

There are Duel-Winning methods in Yugioh; but most of them require some kind of buildup or require multiple turns to perform. Horakthy however wins instantly. Nothing can counter her because a counter must be done after the fact; if the duel was already won then what's there to even do?

True that Exodia is basically the same thing; but only a fully powered Forbidden One (not 'fueled by the human soul of grandpa's grandpa') is a Duel Winner and even then Exodia was banished and dismembered by a spell; so I'm not declaring Exodia to be in this tier because some depictions of Exodia are not all-powerful (especially with the Grandpa's Grandpa idiotic loophole) and Exodia has some magical weaknesses.

Both gameplay-wise and in the anime/manga canon: Duel Winning Infinite Power.

Wicked Avatar is literally always stronger than any monster that fights it (as he is that 'evil more powerful clone' trope), and Yubel - The Ultimate Nightmare destroys any monster that fights her, with Yubel doing more damage against stronger monsters (as she 'redirects the pain' they inflict onto her); yet both will be destroyed by Hora.

And in the lore, Hora defeated the devil Zorc; who had infinite power: 'fueled by the unlimited power of darkness'. This is shown by him dominating the juggernauts of yugioh; the Egyptian Gods Cards (all at once) and Dragon Master Knight.

The-One-Above-All meanwhile; is just that.

Marvel has several dozens of 'gods', even Odin and Zeus, yet OAA is apparently their creator.

But what confirms his all mighty power is his interaction with Thanos; a (kind of) god possessing the Infinity Gauntlet which possesses an infinite amount of soul energy, power, time, ect… For those who don't know, this guy has on multiple occasions threatened the entire universe and all life in it singlehandedly, and has confirmed that he could kill all life in the universe if he wanted to. This of course got OAA's attention. Thanos however could do nothing; because OAA created the Infinity Stones and thus the very concept of power within Marvel. Infinite power was irrelevant to one that is beyond power.

Now what about The Presence from DC? Or the Mother of All Things from Spawn? Again; they should basically the same thing (GOD), I just don't know much about them so I can't make comments. Debating who is better than who is like asking 'is Jesus stronger than Jesus?' Maybe the better answer is:

'You should stop hitting yourself'

Also side note: My Snake Way calculation is actually giving Goku the benefit of the doubt, so my result was an overestimation compared to Death Battle's conclusion.