Most of the things in the Internet of Things (IoT) will include processors, sensors, and a wireless communication path to the Internet, and all likely will be limited to a small power budget. Which one should you use? Bluetooth, Wi-Fi, and ZigBee are different wireless communication protocols that are often accessible as modules for easy MCU interfacing. Compare them in the table below to best fit project needs. The longer reach of Wi-Fi is the reason why Wi-Fi is a dominant choice.
It’s easier to find Wi-Fi either built-in to a development board for your favorite MCU or modules that can be used with a dev board. Bluetooth is next in terms of ecosystem abundance, and Zigbee is last. If you must connect to a smartphone (say you want to program your smartphone to act as a remote for your MCU project) you should use Wi-Fi or Bluetooth. Zigbee modules are well-loved by those who use them due to ease-of-use and reliability, but Zigbee has a smaller market, therefore fewer projects, tools, and other devices out in the wild.