I think it is more driven on which one you enjoy playing at the moment. I most often practice anything on an acoustic because it makes you work for it. When you return to an electric, the electric seems so easy.
With two nice electrics, it doesn't matter as much. I suppose I would say 'play the one that challenges you more' but I'm not sure that the difference in the two really would be all that much.
So, yep, I go with haghj500 > go with your mood.
