Power line adaptors aren't bad, but they are hit or miss. If they hit, they'll work well and solve all your problems for minimal cost and effort. If they miss you'll probably never get them working properly. It's a bit of a gamble, but I wouldn't rule them out.

Wireless range extenders/access points/mesh networks are the reverse. They'll almost always work, but they make the inherent problems with WiFi worse. More latency, more congestion, more interference. They're not without downsides.

Running a cable so you can move your router to a better location would be my number 1 choice. Ideally somewhere where you can plug multiple devices (TV, consoles, pc, etc) into it so they aren't competing with the devices that really need the WiFi.