Which gas is better: Hess or 7-Eleven?

I normally use Hess in my truck (2001 Dodge Ram) but I started reading how Hess isn't too good for your engine (it's apparently cheap stuff that causes problems). Is any of that true, and is 7-Eleven better? I looked at the list of the top tier gas stations, but most of those aren't in my state/local/etc. or they are very highly priced (like Chevron tends to be 15+ cents higher per gallon...). Mobil is cheap and reasonable but, while there are tons of locations in my "area", none of them are actually on my way to/from work and would require me to go out of my way to fill up with them. Hess and 7-Eleven are the only real convenient choices. Which would be better for me to go to? I live in FL if that matters at all.