Home Mesh System vs. Powerline Adapter Advice

Quick background/context:

Moved into a new house years ago, and sorted the problem - or so I thought - with Devolo powerline adapters. I got 3 (one needs to be plugged into the main Virgin Media router), one for upstairs and one for through the back where the TV and office are. It's a relatively large house, so running ethernet it doable but quite expensive.

I have looked at getting Mesh Wifi recently as the performance of the Devolos has been in my opinion, shocking.

The TP-Link Deco are on sale on amazing right now and I was considering that as an option. I'm pretty new and inexperienced when it comes to home networking so please go easy on me :)

• Are Home Mesh systems generally better or worse than a poorly performing powerline system?
• Are home mesh systems truly a mesh? As in, one SSID and Password that ill be connected to through the house?
• Is it worth the money to replace the powerline adapters?