That depends on if you have internet only, or have other services.
any decent router like Netgear or Asus or TP-Link Archer and there are other good ones out there.
if you have tv and want to get rid of the Quantum Gateway Router you will need a splitter and purchase a MOCA adapter to get the guide and video on demand.
the Quantum router can handle gigabyte speeds so your 300/300 is nothing for it to handle. It’s just the WiFi is poor on these Quantum router. And you could always get a Netgear with external antennas and place it in access point mode. There is directions on the Netgear support site and in the Netgear owners manual. And no issue with tv if you have it. But the rental for the Fios router will be $144 a year so you can buy many routers for less on sale. Oh and your internet must be on ethernet not coaxial. MOCA