The best replacement for diet soda is water.

The best alternatives to diet soda are rated as following:
★★★★★  water
★★★★★  regular
★★★★★  regular soda
★★★★  coffee
★★★  soda
★★★  crystal light
★★  tea
★  sweet tea
  flavored water
  non diet soda
  iced tea
  mio
  flavored sparkling water

Your alternative for diet soda is not listed? Suggest!
Speaking about diet soda, one probably shouldn't forget about cake mix.

Other search terms related to diet soda and their ratings are:
★★★★★ cake mix
You have in mind a companion for diet soda and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of diet soda in all years. Click on graph for more.
diet soda
water
regular