I quit using Xfinity gear ages ago and typically purchase one of the lesser expensive modems from their current list (be sure to buy something on their list) with the caveats that it not be too old that it will be knocked off the list soon, and that it be from a known manufacturer with reasonably good reviews, but not necessarily the best.
For routers, I like mesh systems. I have my main system wired directly from the mesh system base router (that is hard-wired to the modem) but my two auxillary systems are hard-wired to mesh satellites (i.e., the satellites are interlinked with the base router unit by wi-fi but the auxillary streamers/endpoints are hard-wired to the satellites). My first mesh system was an Orbi but those have gotten dreadfully expensive. I recently upgraded and purchased a $400 Wi-Fi 7 mesh system from Costco that has been working great (linked below):
TP-Link Deco BE11000 Wi-Fi 7 Tri-Band Whole-Home Mesh Wi-Fi System, 3-pack
BTW, I run both the modem and router from linear power supplies connected to a power line that is dedicated to my network gear and music server in a separate room, and only connected to my main system via a fiber optic line that feeds the Roon endpoint/streamer.