Both the cars are not that great for highways these two are city dwellers. Out of the two Brio is a better pick. Honda is reliable and stable than Hyundai. Brio is 1.2 Ltr engine car (Same as Jazz) and the Eon a 800 CC variant so they are two worlds apart. But if you want more comfortable and good features in your car then must go with Honda Brio.
It is loaded with great features like : Electronic Power Steering, AC with Heater, Central Locking, Tachometer, Front Power Windows, Front and Rear cup holders in central console, Headlamp Adjuster, Headlamp off and Ignition off reminder, etc.
for more information you can see:
Honda Brio Review &
Honda Brio Car