If you have cable internet, you need a modem and a router. A modem takes the internet from the cable company. A router spreads the internet from the modem around the house with WiFi. You need a cable to connect the two.
The modem I currently have. Works really well, has good speeds for most people, and it has great reviews. Choose the speed you need. Cheapest/slowest one is good enough for most people right now, though will likely be obsolete in the next few years.
Router I currently have. Works really well, has great reviews. Good enough for most homes. If it doesn’t reach the whole house you could return it and go the mesh method.
If you want to go mesh, these are the 2 options I would look at. Get this instead of the router. You still need the modem. I currently have google wifi, though they have stopped making it. The new version is the Google Nest Wifi. I’m not a big fan of having devices listen to me. If you don’t care, then this will be fine.
Other option is the UI Access Point. I’ve heard really good things about Ubiquiti’s products, but haven’t tested any of them personally.
If you want one without the speakers/google assistant, you could look at the Asus model. Also have heard good things.