But Stacey L. Savage, founder and CEO at Zero Waste Strategies, a sustainability consulting firm, says what you go for depends on your lifestyle, how much weight you want to carry around (the more the bottle holds the heavier it is), and how big your grip is. In her opinion, though, “a 16 to 24 oz bottle is great for daily use, while a 32 to 40 oz bottle is better for workouts.” From bottles with straws, to bottles with wide mouths, to those with narrower spouts, there’s so much to choose from when deciding what bottle you think is best for you, and it’s really down to preference.