Since pizza is my very favorite food, I have opinions on this:
Best slice - Ben's. Either in soho or 3rd st.
Best whole pizza - Bleecker St. Pizza
John's in the village (the one on 44th is not very good)
Arturo's
Olio et Piu
I am a pizza purist. Other than fresh garlic, I prefer no topping. To put pineapple, mac and cheese, lasagne, salad, etc. on top of pizza is a sin.
<-----I'M TOTES ROLLING MY EYES