M.B.
We have had parties at both and they are both great. I don't think that you will go wrong either way. Consider location, which is closer. Pump it up does have a larger party room, if you are inviting lots of kids (with their parents). They both switch half way through into different rooms. Let's jump might be better for little ones(3 and under). Let's jump does allow you to bring water or juice boxes into the jump room for when they get thirsty. At pump it up no food or drinks are allowed in the jump rooms, but they do have a water fountain in the hall. Like I said before either one will be lots of fun!