Very hard to find good kosher pizza, most places are terrible. But, there are some really good ones:
Brooklyn:
1) My Favorite Bagel
2) Mendelsohn's
3) Pizza Time
Manhattan:
1) Bravos (by far the best kosher slice. Even guy from Barstool gave it a really high score).
2) Sabas
5 Towns:
1) Bravos (Queens)
2) Upper Crust
3) Josh's Brick Oven
NJ: not familiar with many places there, but had EJ's and didn't think it was good.
West Hempstead: Hunki's is very good
Crown Heights: No good pizza there.
Miami: I miss Shem Tov's, that was really good. Miami doesn't have good pizza anymore.