Which Router should I use ?

[SNikS]

Those are all very good routers, but let me ask you, how many device do you have support 802.11ac (wireless AC)? Wile 802.11ac is backwards compatible with A/B/G/N, your not getting the full capabilities of the AC router if you don't have any network devices that support the AC technology. You may just find a cheaper wireless N router will be sufficient unless you do plan to update all your devices to 802.11ac at some point.

You need to figure out what radio frequency you are using. 5GHz frequency doesn't have the range as the 2.4GHz frequency but it does have less interference then 2.4GHz. These home routers have whats called an omnidirectional antennas. When the antenna is at zero degrees (straight up) the coverage looks like a ring spreading outwards.You need to get a router with external antennas that way you can change the coverage area by changing the antenna to 90 degrees. This will allow more coverage to travel up and down. If possible you want the router to be placed in the center of the house.

Some router will allow you to set up a wireless bridge between to of the same routers. This method is very advances and needs to be researched and may not always work the best in my experiences.