Choices, choices ?
After owning a couple or three of these devices, I would say the best I have are the Devlo make. They are the least intrusive. They all take up one electrical socket, exclusively. The Develo are the smallest and have the Ethernet socket at the base, this means the socket at either side on an extension can be used. I also have a pair of Netgear which have worked flawlessly for a couple of years now. The three of the devices are on the same network.
The ones to avoid are Advent, or any that get hot when in use. They all get warm, but the Advent get hot, this is due to cheap capacitors used in them. I dare say there is quite a few more that suffer from the same cheap components. They are also quite large and block any sockets either side of the one being used.