I'm a bit outdated (no AC wireless) but I've been using an ASUS RT-N66U for a long time, with TomatoRAF firmware on it. If you have devices around that don't do N, or don't do N at 5Ghz, as well as items that DO use it, it's important to have a router that does simultaneous networks or else your oldest device will slow the rest of your network.
My place doesn't traverse floors, but the walls have sheet metal in them, and I don't have a single dead spot in my place. I can barely get a signal standing outside of my front door, and it's a heavy ass metal door (think military barracks style).
I will be the last person to die in my lifetime.