Fastest wireless communication
There is a difference between Wifi and Wireless. Wifi requires an already established network and uses the standard internet protocols. If this is what you mean, then the communication speed would only be influenced by the bandwidth of your network and the speed of the arduinos. I have not been able to find what the speeds of the modules are, but if they are 150 mB/s and your network is only 100, then you'll only get a speed of 100mB/s (which is a pretty decent speed).

If you want wireless (they create their own network using the unlicensed 2.4ghz spectrum, then buy these: nRF24L01+ 2.4GHz. They seem pretty reliable at short distances, and have a low power and high power variant. These have a speed of (at tops) 2 mB/s, but you won't have to worry about having a Wifi connection.

I personally do not know much about Bluetooth modules, so I cannot comment there.

Hope this helped.