I think both are nearly the same. It depends how much undervolting can take each algorithm. For me zcash is by a tiny bit less power consuming.
Currently here is a winter with -20 C outside. Inside it is +25 C because I have rigs in each room  . Excellent solution for heating the appartment  . But for the summer it is a hell. Two AC 1200 are not enough. I will need a third AC or have to figure out some way of channelling  the heat outside.