If battery life is a prime concern, you might want to check out HotHardware's review of the Lenovo Yoga C630.
This machine is always connected (with a mobile data plan), it boots up (and shuts down) almost instantly, it breezes through typical office tasks, streams YouTube and Netflix videos with nary a stutter (on both Wi-Fi and via any decent LTE connection), and will literally run all day long on a single charge.
