Which DC1M Supes are you talking about?
The descendant, Kal Kent, aka DC1M Superman:
Is far more powerful than current Clark, but is a galaxy buster (at best) by feats.
The guy I think you mean is DC1M Superman Prime, aka Golden God Kal-El:
In presentation alone, he is far beyond his descendant and at least in Galactus' class, i.e. Universe Buster. But he had pretty much no usable on-panel feats to back up his presentation.
And neither of these guys are the most powerful Superman. That honor belongs to this Superman:
Thought Robot Superman, aka Cosmic Armor Superman, is larger than the DC multiverse and actually has the feats to back him up as a Multiverse Buster.
Zeno wipes out universes with a thought. The first two Supermen can't cut it. The last one? More than a good chance of beating him.