Zoom seems to be more popular, especially for non-business video events. That’s because it is easier to use and doesn’t require registration. Microsoft Teams is more secure. Zoom has better streaming quality. Teams is integrated with other Microsoft 365 programs. Event hosts will choose one or the other based on price and which of those factors is most important to them.
Microsoft Teams is included in Microsoft 365. Businesses and other organizations that are already paying for Microsoft 365 may not want to also pay for Zoom.