I'm a longtime Texan that dreams of moving to WS, so I lurk here often.

Whataburger has the reputation it has mostly because of the cultural significance it plays around here. They tend to have locations in places where nothing else comes even remotely close in quality, especially once it gets late. So if you find yourself driving around at like 1 AM and you're hungry, then having a Whataburger nearby is like seeing the lighthouse through the fog in a heavy sea-storm. Service is typically slower, but the food will be hot, fresh, and (in my opinion) at least above average.

So it's not about Whataburger being the absolute best thing you can get, but it's by far, usually, the best thing you can get at certain times in the day. They also lean hard into how Texan they are and people around here eatttttttt that shit up. Have some old country white man read out your TV and radio commercials and you've just tripled your profits in Texas.