You have to think about more than reputation. UW has a better one, but it also is a very different feel. Would you rather be an unknown in a large class or be well known in a small class? Because UW only has 63 students, everyone knows everyone, and that includes faculty. I may be a little biased because I go to UW, but I love being in a small class. I can't attest to NYU but if you have any questions on programs/living in Seattle feel free to PM me.
Also - you should definitely take cost into factor. Regardless of the school that you go to you will graduate as a dentist. How much school costs greatly affects you down the road!