My project is about creating an energy efficient routing protocol for Wireless Sensor Networks. I wanted to ask, is Omnet++ better for this or NS2, NS3?
I would also suggest you look at NetSim once. You could look at their IoT/WSN page https://tetcos.com/iot-wsn.html and also their file exchange page (https://tetcos.com/file-exchange.html) which has documentation and codes for various projects related to energy/power management in WSN/IoT.