So.. is it?
If not, what item and/or Being trumps it?
I can't think of any items that may be more powerful (I don't THINK the Ultimate Nullifier is, though I'm not totally familiar with it), but can't the Living Tribunal "turn the Gauntlet off"/etc?
To give DC its due, I'd think the Anti-Monitor could give it a run as I remember him as being an "ultimate bad-ass", but I remember in the Sinestro Corps War (last time I saw him), he was a bad-ass until Superboy-Prime got "tired of him" (spoiler-free
).
The Gauntlet would spank Super-Boy Prime with just one gem, while forcing Omar to watch.
Obviously items like Mjolnir rank up there as well, but even that pales in comparison.
Thoughts on this?