Last I checked, powerline adapters had really high latency. That was a few years back though. Have they resolved that now?
I disagree that wireless is inherently bad for gaming. 1ms latency to a wireless router is perfectly normal. A lot of it has to do with the how solid the walls in your house are, as that can rapidly deteriorate your signal. Line of sight improves wireless signal massively.
What you might want to check out is whether a neighbour has introduced a competing wireless network. Although there are a lot of wireless channels, there are only three that don't actually overlap in regards to their use of the frequency spectrum, and overlap causes problems. The cleanest channels are 1, 6, and 11.
This article is pretty good for getting you on the right path: http://www.extremetech.com/computing/179344-how-to-boost-your-wifi-speed-by-choosing-the-right-channel
I used Meraki Wifi Stumbler to see what channels neighbours were using, and how strong they were in different areas of my house. I found it to be quite easy to use.
Not sure on the power-line adapters, I've never used one... but in theory they should be very fast. They just use your power lines to transfer data in pretty much the same way that ethernet transfers data - or so I thought? I don't know the difference from an electrical standpoint but... ethernet transfers data via voltage, I figured the power-line adapter did the same thing?
Wireless is strictly worse than having a hard connection for everything. There's just no way around it. Sure it is way more convenient but it is slower, less reliable, less secure... even in a good environment there is a lot that can go wrong. (channel overlap, broadcast bandwidth getting backed up, interference from other devices, objects disrupting signals, etc)
Multiple devices using the same wireless router/access point can cause issues, unless you get a multi-band device. Basically, the way I see it... any wireless router good enough to let your family troll around on Netflix/Youtube/torrent stuff while not having any effect on your game is going to be expensive.
Or you can buy a $10, 100 ft cat5/cat6 cable and have a perfect connection without having to worry about anything.
I'd be interested to see if the power-line things work well these days though. In theory they should be good... maybe in practice they just suck.