Choose WIFI or Bluetooth for tethering connection?

[petalino]

I've never had tethering before.
Now I just bought a used unlocked Iphone 4S and am using it with Tmobile voice, text and 2GB data plan with tethering.

When I turn on tethering, I am being asked if I prefer to use WIFI or Bluetooth tethering.
Which one should I prefer?
Any advantages or disadvantages with using one or another?

I am tethering the data plan to Ipad 3.

Thanks in advance

 

[Menel]

Bluetooth more persistent, less battery consumption.

WIFI is faster.