If you're looking for the hands-down best option for ounce-counting adventures, the Hydrapak Shape-Shift Reservoir is for you. It has a simple design and slim profile, making it race-ready and compatible with any running or hiking pack. The zip-lock divider prevents water from sloshing around, while the flip top opening makes for easy cleaning and fill-ups. The blaster valve delivers water quickly with little suckage required, and the quantum clip keeps the tube in place. It fits comfortably into packs of all sizes but might need a little bit of work to wiggle into place when the pack is full.
This bladder withstood freezing and laying out in the sun. It has a very similar construct to the Geigerrig Hydration Engine, our Editors' Choice winner except it is not pressurized. Flip it inside out and throw it in the dishwasher for a good clean. While it doesn't have as burly a construct as the CamelBak Crux, it is surprisingly durable. This is a simple and easy-to-use system, winning a Top Pick for minimalist escapades.