The verizon device can operate as a normal router and use a ethernet port rather than the DSL to connect to stuff.
So IF your comcast device is ONLY a modem then you could use this as a router. Not real sure you want to it is very old technology. It only does 802.11g.
If your comcast device is actually a modem/router then I would use that device. You could I guess use the verizon as a AP to support old 802.11g client so you could run your main router in N only mode.