Best wifi range extender?

If you have an Apple router then the easiest is another Apple wireless product.
Very easy setup as an extender. Apple store refurb would be a good place to look.

 

There's your problem. Most Verizon routers have horrible range.

Run an Ethernet cable from it to another base station like the AirPort Extreme or express and us it as your primary access point. Just use the Verizon box as a router, not a wireless station.

When my house was built, all the cables were run into the garage. I have my cable modem and a router out there along with my VOIP box and then have an AirPort Extreme in the middle of the house that provides great signal everywhere.

 

Run from your modem an ethernet cable into an AirPort Extreme or Time Capsule WAN port and use AirPort Expresses via ethernet cable to extend WiFI points if needed.

I find an AirPort Extreme or Time Capsule as the base/primary router with one or more AirPort Expresses joined via ethernet cable is the best setup. The wifi extending exercise is seamless and the two (Extreme and Express) work really well together as they are designed that way. I have tried other range extenders on the Extreme/TC and also tried the AirPort Express to extend a non-Apple Router (Cisco and TP-Link). I have had some luck but with non-Apple & Apple configs but they are hit and miss.

Setting up a full Apple (Extreme/TC+Express) network is dead easy and coverage/strength is by far the best I have seen, particularly for Mac/Apple devices.