You don't really get a "modem". You get a box which converts fiber to RJ45. After that piece, which CenturyLink does not charge you for monthyl (as they do their router) you can use any manner of device to act as your internet gateway as long as it has two NICs available, and can apply VLAN tagging to a specific PPPoE connection (the nic you plugged into the medium changer). I personally am using a pfsense VM with two physical nics made available via KVM passthrough, but you could use any modern Asus commodity router, Netgate box, spare computer with two nics, etc.

Beware: the standard Centurylink wifi router thing has WPS enabled by default, and you'll really want to disable that if you use it. This is one of the reasons I don't recommend people buy those kinds of things anymore. You're much better off going with a standard linux machine acting as a gateway, and having a proper AP like a Ubiquiti Unifi AP Lite for wifi duties.

Aside from that, they are significantly cheaper, for gig service, than Comcast was for Blast. No cap, either.