A mile away ?
I try to "eat local" whenever I'm on the road, and often superchargers are in places that have mainly national chains.
I know that even national chains employ local people and are often owned by local franchise owners, so that still helps the local economy.
However, it does seem like I can find fresher, more healthy food at true independent restaurant. (Whether I always order something healthy... well, that's different.) Also, I'm more likely to get something interesting at a local restaurant. The whole idea of a chain is that it should taste the same wherever it is. Nobody says, "Try the McDonald's in Abilene--it's got a unique taste."
Of course, this means I don't always get to take advantage of eating while supercharging, unless I get it to go before going to the supercharger. But on a road trip, I tend to "supercharger-hop" and only charge 10–15 minutes at any one supercharger, so usually spend that time taking a bio break and stetching my legs to get some exercise. Lunch is dinner is a good excuse to get out of the car for at least half an hour.