When I was shopping for a hydration vest I asked a lot of ultra runner friends what style and brand they prefer; for the women, the most popular choice hands-down was the Ultra Vesta from Ultimate Direction.
First and foremost, the Ultra Vesta is women-specific – not your typical one-size-fits-all hydration vest. I have a small frame so I ordered the extra small and it fits comfortably with minimal strap adjustments. If strap adjustments had been necessary, though, there are endless options for adjusting and personalizing the fit.
Fitting closer to the body like a vest rather than a pack, it hugs the body nicely and stays firmly in place, no matter how much gear you fill it with. My Ultra Vesta model has a maximum water capacity of 3L; I can carry a 2L bladder in the main compartment (not included), and two 500ml body bottles in the front pockets. The body bottles are included with the vest. Fully loaded, there are additional pockets for cell phone, keys, gels, etc. I like to be completely self-sufficient when I run, so I really appreciate the amount of pockets in the Ultra Vesta.
The Ultra Vesta comes equipped with straps for carrying trekking poles, as well as an attached whistle, and an emergency hair elastic tucked into one of the pocket.
I have recommended the Ultimate Direction Ultra Vesta on many occasions; I appreciate its comfort, ease of use, storage capacity, and it looks nice, too.