The power line units work well in many cases, especially with homes built in the last 30 - 40 years. Make sure your home has a good ground on all affected outlets, and that you have one circuit breaker box. (Often times the connection will span separate breaker boxes very poorly, if at all.) Also, if your home is wired with a central (break box mounted) ground fault adapter, it is very likely the power line units will not work well. If you have GFI outlets near the bathroom or kitchen sink, you’re likely OK.
I am using several TP-Link AV 1200 units with excellent results. These units make use of all three wires in the AC circuit and require a good ground. I see about a 30% - 50% drop of signal from the back of the main router to the power line unit. (This will vary some, based on local conditions and appliance usage.) Some TP-Link AV1200 units even have a built-in wifi router (both 2.4gHz and 5gHz) to provide additional wifi coverage to the rest of the house.
My Tablo is in the sunroom, with the Plex server in the front office. The TVs and Rokus all connect via wifi. Move gigabytes of data through them daily with no hiccups – even when multiple people are streaming.
Power line extenders look like a piece of wire from the prime unit to the remote unit. They are truly “plug-n-play”, unless you get the ones with a router built in. My have only needed to be unplugged and plugged back in a couple of times in more than a year.
A bit of advice: stay with one brand of power line extender and one speed. While supposedly compatible, many systems do not work well together. Also, NEVER connect a power line extender through an extension cord. It will work very poorly, if at all. Also, I tried to save money by using units slower than AV 1200 (AV500, 600, etc) and was constantly disappointed. Many dropouts.