using the weapons attack power alone is a terrible way of determining a weapons actual power, especially considering that affinity is a percentage.
without going into the more accurate math, heres a simple dps based on a simpler model than the actual damage calculation:
1248 + (1248 x .25)= 1560 as you said, but the affinity is 50% meaning roughly half the attacks are at that power.
so, though as i stated this is dreadfully inaccurate, this would be the cumulative power of the two weapons in 4 "attacks":
Hmm... so, despite the oversimplification, the hypothetical dps is the same. however, 50% affinity does not mean every other attack will be a critical, so by means of consistency, juggernaut is better.
And besides power, juggernaut is far easier to make than deep darkhammer.