What's the best comunication protocol for a sensor network?
All of those you've listed use 802.15.4 as the physical radio layer.

802.15.4 is a good choice as there are many chips from semiconductor makers that have this radio. Also look into BTLE.

A great way to get started with 802.15.4 and 6lowpan is with the Contiki Operationg system and Econotags.