What is the best Japanese Restaurant in America?

It would be easier to answer a question asking for "the most profitable", or "the largest" or "most locations" or "most customers" or "most name recognition". Some specific quality. But asking for just the "best" is tough and depends on the parameters you seek, including fast-food vs sit-down restaurants, burgers vs coffee, seafood vs steak vs chicken, career paths, etc. Some chains are quite regional. Sonny's BBQ and In-N-Out Burger don't cross paths.

For the biggest in sales, in 2016 McDonald's topped the list at $36.4 billion. Starbucks rang up 2nd place at $17.9 billion.

For the chain with the most stores, in 2016 Subway led the pack with 26,744 locations, followed by McDonald's (14,155) and Starbucks (13,172).

If you are looking for the sit-down chain restaurant with the best food, that is very subject to opinion. Two different published lists both included Cracker Barrel and Texas Roadhouse in their top 5. The rest of their rankings were quite different.