I grew up in Niagara Falls and had my first taste as a very young boy. I haven't lived in the Falls for almost 30 years now, but every time I visit, Viola's is the first stop, even before getting to the relatives house. It is a combination of some of the best bread in the world (Niagara Falls has absolutely the best bread bakeries in the world - and I've been to nearly 30 countries and every state), fine sliced Delmonico steak, and white American cheese (many think it is provolone, but it is white American). The perfectly seasoned toppings and oil is what is not reproducible, no matter how hard I've tried! And is what makes this so much better then Philly steak & Cheese subs.
Either venue is as good as the other, although many locals prefer the Elmwood ave location. Enjoy!