I find Zoom to be the most accessible virtual conferencing tool on my iPad. It works well with VoiceOver and the controls are intuitive. It also works well with groups which makes it easy for me to continue weekly group meetings with my research students and my access assistants when working remotely. Zoom is dedicated to making their platform accessible to all users, and they state that their products support common screen readers like JAWS and VoiceOver. To find out more about Zoom, check out: https://zoom.us/
Microsoft Teams is not accessible to me on my iPad, which is my primary tool for remote work. Although Teams is available on Mac, there are a few major accessibility issues with screen readers (as of April 6, 2020), which depends on whether Teams is interfaced using a web browser or a desktop client. I hope that Microsoft will fix these accessibility issues soon, as I am unable to attend and participate in some meetings and workshops. For now, my workaround is to ask the host to share slides or a copy of the recording, if available.
Overall Skype and Skype for Business are accessible, but I've found that some of the features do not work well with VoiceOver and are difficult to control. For example, I am unable to use the screen sharing feature when using Skype on my iPad. This makes it difficult at times to work with my access assistants remotely. For Windows users, Skype does have a build in screen reader for Windows 8 and above, but according to their website it may also work with other third-party screen readers such as JAWS. In comparing Skype and Skype Business, I've found Skype is much more reliable. Skype Business had difficulty connecting and maintaining calls, which is counterproductive.
I've also tried to use Google Meet for video conferencing, but it did not work well. The other attendees were not able to hear me, even though my microphone was unmuted. This may be more of a technical problem instead of an accessibility issue, but it is not ideal for working remotely.