I've been tempted by the new WiFi mesh routers recently but to be honest, I could not justify the purchase because my Asus RT-AC68U router was doing the job and I had no dead spots. However, changing it would provide better performance but what to do with the old one? It's working perfectly!
I then discovered that Asus updated the router firmware with mesh capabilities called AIMesh. Basically, you can now create a mesh network using a list of supported Asus router. Now that cool, especially since BestBuy had a one day sale on the RT-AC86U this week :-)
Setup is super simple, you update the firmware of all the routers. You use the one with the best performance as the primary router, you reset the node router and activate the AIMesh search on the primary and once discovered, you join the node in the mesh network.
Here's a screenshot of my RT-AC86U showing the RT-AC68U as a node with one client connected.
I tried powering down the node to see what happens. The device simply reconnects to the primary router. Sweet!