The newest set from LEGO. When not sure, choose this. There are two sets - Prime and Prime Expansion. Take both of them. It is worth it.
It is slightly more advanced (and powerful) but not that colorful as the SPIKE Prime sets. Probably that's why it is slowly fading away. People often choose the SPIKE Prime set, but Mindstorms EV3 is still strong.
A cheaper version of LEGO Education SPIKE Prime. Basically the same capabilities, but with fewer parts to build with.
You can start with the Scratch course while you are waiting for your robots to arrive. It requires a computer.
Suitable when you want to try someting different - like a Raspberry PI. It is more advanced and requires more from you. It is a great introduction to IoT, Electronics, Python programming, Machine Learning & AI. Students will use raspberry pi as a platform to program a RC car to be controlled by their smart phone. Then add sensors and make the car "learn".
VEX IQ is quite popular with competitions and with teachers. We don't know a lot of people that are using it at home. If you have VEX IQ you can start by following these resources.