what's an AC-based wireless router?
Compared to what?
AC is the newest type router. The ones before were “N” routers. Can’t remember all the improvements...just google AC routers.
802.11 AC gigabit routers are the new protocol for routers. They have better Wifi speeds among other features. I find they don’t last as long as the older N designation routers, but they’re lightning fast compared to them so it’s worth the money. Depending on how many wireless devices you run in your house, you should choose one that has an appropriate number of internal/external antennae.