I use a Asrock J3355B for my little nas/homeserver it idles at 8W and "spikes" to 15W while decoding movies. It's a bit pricier as a raspi but it has a lot more

I use a Asrock J3355B for my little nas/homeserver it idles at 8W and "spikes" to 15W while decoding movies. It's a bit pricier as a raspi but it has a lot more features. 2 Sata Ports, PCIEX Slot up to 16gb ram etc but most important it is completely silent.