AC is newer, and all things considered, better. Better in the sense that with equivalent connections, the AC router will have a higher data transfer rate than the wireless N. Range won't be terribly different though. Of course that's assuming you also have a wireless AC capable adapter on your device or PC. Personally, unless the prices are similar, which they're generally not, I'd go with a less expensive wireless N dual band unit. Just make sure it's a high data transfer model like N600 or higher.