Depending on the state, I'd much rather have a bio break, snack, and stretch my legs at a rest stop. Picnic benches, shade and a view, even a pet relief area. Many have water stations to refill bottles. Does require I've stocked the car with meals and snacks. In general filling stations lack the nicer amenities, most just suitable for gas and go.
Source: Just did 6338.5 miles encompassing 16 states.