What are some alternatives?
When comparing Ordering Stack and Square for Restaurants, you can also consider the following products
SambaPOS - SambaPOS is an open source POS Software for Restaurants.
Lavu - iPad Point of Sale System
Lightspeed POS - retail and restaurant point-of-sale, ecommerce, and omnichannel solution
Brigade POS - Brigade is a full service restaurant point of sale system.
TouchBistro - iPad based Point of Sale solution for restaurants
CAKE - CAKE provides a SaaS-based solution for advertisers, publishers and networks to track, attribute and optimize their spend in real-time.