Which Tethering Is Best?

USB Cable. If the device you're connecting is able to connect to your smartphone or tablet (whichever device has the data plan that you're using to tether through), that's probably the best option. Tethering consumes energy by expending power through the antenna to communicate with the carrier.

Which tethering method is fastest?

Wi-Fi will provide you with the fastest connection, and a more reliable one than Bluetooth. That being said, it will be the biggest battery suck of the three available options, especially when you're tethering more than one device.

Does tethering use more data than normal?

Finally, wireless tethering tends to take a lot out of your smartphone's battery. Maintaining a constant and intensive connection to the internet, and also to your tethered device, consumes a lot more power than regular smartphone tasks.