The three 20oz tumblers were packed with 6oz of crushed ice, using the exact same amount of ice in each, and sealed them tight with the included lid.
Then, after waiting 12 hours with the cups untouched on a kitchen counter, It was measured how much ice had melted.
The Yeti, Ozark and Rtic lost exactly the same amount of ice into water: 2oz.
So at this point we are all tied up.
At 24 hours, I cup drained each cup again.
The Yeti and Ozark lost identical amounts once again, 2 ounces and the RTIC lost 2.5oz. The Yeti and Ozark were tied.
Finally, at the two-day mark, 48 hours, all the ice had melted. except for one tiny piece of ice remaining in Walmart's Ozark Trail cup.
So in the end we're calling it a tie, between the Yeti and Walmart's Ozark Trail. Both did an excellent job.