Plain fluoridated water is still the best option, but sparkling is far better than soda or sugary drinks.
Sparkling waters don’t damage your enamel the way sugary drinks do. You should be careful, however, not to drink too much citrus sparkling water. Citrus flavors have a lot more acid which can eventually breakdown your enamel. The ADA recommends not sipping on sparkling waters throughout the day but instead trying to finish it off during mealtime.
Read more here: Mouth Healthy – The Truth about Sparkling Water