If it were me, I’d buy a TP-Link Deco AX3000 WiFi 6 Mesh System (Deco X55) (or similar). Instructions are simple. Set up one as your main on the 1st floor. Set up the other two as satellites and make sure they’re all working on the 1st floor. Once they’re good, move one to the the 2nd floor and the last one to the 3rd floor.
For good quality, place each unit where you need the most Wi-Fi coverage. For better quality, find a good low voltage installer and run wired backhaul. In other words, run 1 Ethernet cable from your main unit to the satellite unit on the 2nd floor and another cable to the satellite unit on the 3rd floor. A good installer will run the Ethernet cables behind the walls and termionate to a wall jack. You’ll need an Ethernet patch cable to run from the jack to each Deco. Hopefully, the townhome is already wired - maybe find that out before you move in.
Older homes may have coax cable used for cable TV. There are adapters, called MoCA, that can connect to each end of a coax cable and then convert the signal to Ethernet. That’s another way to do wired backhaul to the Decos.
Last, but not least, find out who your Internet service provider (ISP) will be before you move in. You may need another device, such as a modem or optical network terminal (ONT), and you would connect your main Deco unit to that.
Good luck!
The TP-Link Deco line is tough to beat. You have the option to run mesh (meh) or use wired backhaul for better performance.