In our experience, Zoom is best for this. It’s the most widely used and the easiest to navigate. We are also able to use MS Teams and Google Meet, though they’re not quite as functional. Webex is a last resort as it has poorer connectivity in comparison to the others and is less user friendly. MS Teams allows the fewest number of people on screen at one time. However it does work well for arranging the communication of the quiz teams themselves if you have it on your company systems.