What special about Apple AirPort Extreme?
Wireless is a complicated topic and you need to consult a speciality website like smallnetbuilder.com if you want to understand things like range, performance, and capabilities of different routers.

The Apple Extreme/Express are more expensive, require an Apple utility that runs only on iOS/OS X/Windows, and are not the most feature rich.  However, they are simple to use if you live in a mostly Apple world and have some unique Apple features that can be useful in that world.  For example, it's dead simple to wirelessly extend an Extreme/Express network and Apple Express routers can be hooked to speakers to use with AirPlay.

I just used three Expresses to replace an old 802.11g network (it used four old Linksys routers wirelessly extended to get about 50% coverage) at a friend's condo.  It's only a single floor with about 2500sf but the walls are all steel-reenforced concrete so wireless range was extremely limited.  It took all of about 10 minutes to install three units and network them with a single SSID and WPA password.  I would have preferred wired connections but it wasn't a practical option due to the construction.

I can't see much advantage to the Extreme over the Express with the current models unless you want to use the gIt might have better antennas and thus better performance but I think that's an edge case. It also may have some additional features so you'd need to do a feature-by-feature comparison.