Ethernet cable will be about 5 times faster if you are in a busy area.
In my small midlevels flat, the computer connected by ethernet get 90% of the promised speed of connection where the wireless get about 20%.
There is too much interference with so many networks in the area.
In short, cable is the better option and it also has advantages in that it is a more secure network (No listening in that can occur with wifi).
I have no experience of the homeplugs but they sounds interesting
