Who are the top manufacturers of video conferencing systems?

Personally, I think these are not bad: Feimei, good meeting, full-time job, but which one is good enough for people to evaluate, you have to test and compare it yourself. After all, the video conference system is very mature now, and the basic functions are similar, but the protocols and core technologies adopted by various manufacturers are different. The most important thing is that you should consider that you bought not only the system, but also the service, so after-sales service is also very important.