IOGear 12,00 Ultra Capacity Charger
Another brand that isn't very well known, but has some great portable battery chargers is IOGEAR. Their 12,000 mAh charger is the perfect middle ground. It's not too big, nor is it too small, yet it still features a big capacity and two USB ports to charge more than one device at a time.
I gave mine to a friend, and he's constantly charging his Galaxy S6 and Vapor E-cig at the same time. Perfect right? Like most portable battery options it has an LED for battery levels, an easy on/off switch, but like most recharges slowly via a standard micro-USB cord.
The IOGEAR is a perfect size that's bigger than most 10k chargers, but not so big that it's no longer what some would consider "portable".