What alternative education do you think is better, Montessori or Steiner (Waldorf)...and why?

We're not sure if we want to send our kids to a Montessori or Rudolph Steiner school. We want to start them where they end up -- so we have to make a decision soon since our son is 3 years old. I really like the concepts of both types; however, Waldorf is significantly more expensive (almost double), and I'm wondering if the extra money is worth the end result...especially high school, in which the tuition is equivalent to a 4-year university! Thanks in advance for your answers!