"...........to back up around 1tb of data..........I want to experience the best transfer speeds ideally."
USB will provide the best transfer speeds. USB2 operates at a theoretical maximum speed of 480 megabits per second, while USB3 is significantly faster at up to 5 gigabits per second. You can tell if your computer is USB3 equipped by looking that the sockets. If they've got a blue bit like this, then they are.
"Also, my wireless network is standard 'N'."
The wireless-N specification has a theoretical maximum speed of 300 megabits per second. However, a lot of routers and wireless adapters are "N lite" versions that have a maximum speed of just 150 megabits per second.
If you're going to be regularly backing up 1TB of data then I think you're likely to be very disappointed using a WiFi connection.