What router for USB tethering to android

I'm looking to buy a router that can use my Android phone (through USB) as its internet source and create a WLAN. The router must also support tunneling through a VPN. I currently achieve this using a laptop (running Windows 7 using PdaNet for Android and PIA as my VPN provider) so I'm hoping it's possible with a router. Networking is not my expertise so I have a couple of questions:

  1. What router should I buy?
  2. What firmware should I run on it?

Right now my research points me to the ASUS RT-N16 running DD-WRT. It would be great to hear from anyone who has done this or is thinking of doing this.

I had horrible performance issues on my RT routers with DD-WRT so on my AC68P I'm using Asus-merlin. I know that it has USB WAN failover mode which you can set as the primary USB WAN, and of course supports VPN. I don't think you'll be able to use PDANet though since it has a proprietary aspect to it. If you use the stock tethering, on most android build it's RDNIS based which is supported.