I've become a huge water drinker over the past year or so and like others here I love it with fresh lemon or lime squeezed in. Citrus naturally helps burn certain fats so it can help with weight loss as well.
I don't drink alcohol anymore and rarely have a diet soda, so I primarily drink San Pellegrino with a dash of sparkling blood orange or grapefruit juice, coffee in the morning with a little honey and half/half, and unsweetend ice tea.
We also juice one meal out of the day (usually dinner) and it has made a huge difference in every way imaginable. Once you get hooked on the zing fresh fruit and veggie juice gives you, there's no going back!
I'm not a big stevia lover. It's way too sweet for me. I love agave nectar and local honey though and cook/bake with them as much as possible.
Stay away from artificial sweeteners...nasty stuff! Good luck