Water has been discussed many, many times on this forum.
There are extensive threads detailing things like total dissolved solids, pH levels, flavor, etc. of various kinds of bottled water and the effectiveness of different kinds of filtration and purification systems.Here is one such thread
Personally, I find that, for everyday drinking, nothing beats the cost-effectiveness, ease, and taste of filtered tap water using something like a Brita pitcher. For special occasions and teas a nicer bottled water like Iceland Spring can be nice.
Green teas and high roast oolongs are often better with different water though, so there's no one magical water for everything.