The coldest water bottle is Topo Chico.
The Topo Chico truly does keep your water the coldest. It has a natural low PH and 36% less dissolved solids than tap water, which means it takes up less space around the ice cubes and doesn’t let anything stick to the cubes. All of that combined with its design makes for packing down quickly and keeping ice in surprisingly long compared to any other typical water bottles – even glass ones!
Both major benefits of this were clear when I took my typical 1 gallon jug out on top of topote clicco hike to go climbing in Joshua Tree National Park (CA) = 4 hours without any ice left.