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My family owned a water company the whole time I grew up until my dad passed...
I personally find water to be best at what I refer to as "buoyant".
The water should be the same, subjective, temp as your body. So when you drink it, you feel only the physical properties of the water, not warmth, nor cold.
I can drink a LOT more water this way - and it helps with hydration, which is different to cooling or warming the body.
Only rarely do I like ice, but when I do ; crushed.
But body-temp water is ideal.
Unless I'm in Arizona. In Arizona I fill the glass halfway with crushed, the rest with cubed (keeps them from organizing batallions against your face) and then with any fluid I can get my hands on.
(I guess another caveat is when I'm in California, where my M. O. is that of burning through crates of whatever brand of lightly-flavored canned sparkling water we're on that week.)