From a weather standpoint, both look to be good, with no bitter cold.
I can say that the ice statues are judged on Thursday morning, so that is when they are at their very best. Most still look very good for Fri-Sat, but the longer they sit, the more time there is for some quality loss.
So I would say you could probably do either with little difference. Saturday at around 9 there is a torch light parade on the slopes of Mt Ripley and then Fireworks, so if you plan to stick around that late, could be a deciding factor.
More here:
MTU Winter Carnival
-John