It may not be a New York slice, but I'm a fan of Marco's pizza. No Thick but decent crust, tasty sauce, wide selection of toppings (try the Triple Pepperoni Magnifico!), reasonable prices. Like Domino

The triple pepperoni pizza is the best. Their pizza heats up better than other competitors for leftovers.

Not the worst pizza in Frederick MD, but pretty close. As for customer service, it was the best non-verbal f*** off I've experienced.