Not sure it will work with the Pi3's but the TP-Link UE300 seems to be one were a number of folks report success with. But not everybody seems happy with USB ethernet. And there are better ARM based boards around to base a router on. What the pi's have going for them is their relative large number and so far decent track record at fixing bugs and developing new versions while keeping older ones still available.
In which case I would start with your existing HH5A configured as dumb AP.
If however you want newer WiFi and OpenWrt, I believe this thread might be interesting: Belkin RT3200/Linksys E8450 WiFi AX discussion