I'm sensitive to this because the SO is violently allergic to corn in all its forms. The "Juice Squeeze" line of bottled beverages seems largely free of HFCS, and Piedmont G offers several regional brands of sugar-based soft drinks, probably unavailable in your area (although their "Dad's Root Beer" is also an ADM no-fly zone for some reason).
I seem to recall reading that, NAFTA notwithstanding, Mexico still attempts to protect its domestic sugar industry, and that in consequence ADM has not yet overwhelmed their soft drinks. I haven't researched this, so some Googling would probably be prudent, but a local Mexican restaurant we patronize sells name-brand sodas bottled in Mexico that do not, so far as I can parse and translate the listed ingredients, include HFCS in any language. If you have a Hispanic district in your area, you may be able to pick up imported "kid pleasers" at the ethnic retailers.
cordialisimo,