1 vs 4 ohms won't make much (any?) difference if the power level is similar.
Generally, an amp's efficiency will drop a little as it gets closer to minimum impedance, but only by a few percent.
1000w at 4 ohms vs 1000w at 1 ohm probably wouldn't amount to more than a 5-10% difference in current draw assuming the amps are the same class.
SQ -- pretty subjective. The main difference would be damping, but at ~1000w to a pair of 12's I really don't see that as a major factor unless it's a POS amp with an exceptionally low DF to start with.
So technically 4 ohms would be preferable to 1, but realistically it's not likely you'd hear a significant difference based only on impedance.
However, you'd probably pay twice as much (or more) for 1000w at 4 vs 1000w at 1.
ppi1000.1 would be a good fit.