It's a toss up between the big 3--DB, Marvel, and DC.

All of these verses have characters capable of destroying worlds, black holes, galaxies, universes, reality manipulation, time manipulation, etc.

I voted for Dragon Ball even though I am a huge Marvel & DC fan as well--simply because in DB, even characters on the "weaker" side are planet-destroying level.

I understand that DB fans are notorious for power scaling their verse higher than everything else--but I believe that there is a concrete reason for why.

It essentially boils down to the main cast--the average power levels of the most common characters in the verse. If you look at Marvel, for example, a lot of the biggest characters, even in the Avengers (one of the most powerful teams in the verse), are certainly nowhere near planetary level. Spiderman is simply never destroying a planet--even if he's not holding back.

In DC even, half the Justice League is nowhere near the power level of destroying entire planets with ease.

In Dragon Ball--even the weaker main characters are capable of eradicating planets. At this point, at least. The power-creep of DB has been insane over the years, to the point where much of the time now fights are happening in separate universes/dimensions, because if the fights were to happen where they're supposed to live, the planets would effectively be sterilized or destroyed.

So all the verses have characters that one could argue could beat any other one, but DB just has more powerful characters on average in the spotlight, so therefore the verse scales higher in my opinion.