I've used RAVPower in the past. It's not bad, but it's nowhere near Anker. I've had RavPower bricks fail in the past - but their adapters and plugs are nice and really cheap sometimes on Amazon.
However, if you're going for a power brick - highly recommend Anker. Keep an eye here on Macrumors and Amazon - you can find some REALLY good deals on those things. Spend some time learning which ones are current generation and last generation - you can find some 50% off deals on the older generations sometimes.