using my own router

I own a 7000 sq house, it is L shaped and it happened that the modem/router location is far away from most of the houses rooms. Unfortunately the XB8 wifi can cover only 30% of my house. I want to use my own router/mesh.

I want an honest opinion from Xfinity support team. Which option had more success in the past?

Option 1: turn on the bridge mode in XB8 ? vs Option 2:  Buy a third party modem (without router)  form the list recommended by Xfinity.

To note: I have 1 gig internet service with a possibility to upgrade to 1.2 Gig plan in the future.