Personally I think PLC based system would make most sense for home automation, considering that a large portion of the devices are mains-powered anyways. And if you design the system really cleverly then having the same network extend wirelessly to those nodes where PLC is unsuitable.
Powerline control is fine, but X10 is simply too slow to handle the demands of a modern house with advanced automation. My own system uses DMX-512 and Philips Hue lights (which use Zigbee Light Link). Some of my customers use X10, but the performance is not nearly as good since it can only transmit 20 bits per second.
