I now have both Elite Fly 950s and Polar Breakout 30 oz. After some usage, the caps on the Elites leak but also fall closed too easily when drinking. The Polars just seem more rugged, a bit closer to the Camelbak Podiums. I like the cap design on the Polar - simple yet removable. Less complicated than the caps on the Camelbaks.
For now, the Polar is winning for me. My N=1.