Depends on how old your wiring is, IME.

Powerline can work really well if the wiring is good. Otherwise you’ll be better off with extenders.

If your electrics are in good order - proper ring mains and the like - powerlines can work quite nicely. Could you find someone to lend you a couple to try? To meet the same problem as yours, but with dodgy electrics, I bought one of these [url= https://www.amazon.co.uk/dp/B01N7TQXTX/ref=pe_3187911_185740111_TE_item ]TPLink [/url]jobbies and threaded a cat5e cable through from the router. The neat thing with this set up is that the box can take its power from the cat5e cable so no plug needed. Provides a really strong wifi signal.

Wifi repeaters are a bit rubbish, I'm using some cat5 and some wifi powerlines and they're 'fine' we're getting about 50Mbps out of them from a 100Mbps line.

Extenders will halve the speed for each one e.g. 50mbps at the router, 25 at the first repeater in the middle of the house, and 12.5 at the far end on the second repeater. Go for powerline if you can.

Extender didn't work too well for me. Powerline system is performing pretty well. Both systems made by the same company. Problem with wifi may be due to how the house is constructed though (lots of concrete and steel joists).

We have an extender so the internet reaches the downstairs loo. It's okay, it does the job it was meant to, but all our devices seem to get confused when going from one to the other. It's annoying when you're waiting for a device to realise you've moved and start working again.

I'm tempted by powerline adapters, but two devices on all the time just so we can use the internet on the loo seems a very inefficient use of power...

If you're anywhere near Fife/Dundee I have a pair of BT powerline things you can have