Around - Provides an interesting focus on speakers/attendees which float around your workspace as heads within circles. The emphasis is putting focus on your face while minimizing background distractions.

Jitsi - Provides an active and open source solution which has been around since 2003. Provides dial-in, recording, simulcasting, end-to-end encryption, and more. I’ve had trouble with this service in large groups using the free version but maybe the paid version performs much better.

MakeSpace - Provides another innovative solution but has no visible product offering I’m aware of. Worth keeping an eye on, though.

Remotion - Provides a similar experience to Around where everyone you communicate with is a floating circle.

Strive - Provides an open source video conferencing system with support for breakout rooms, screen sharing, polls, multi-languages, etc.

Tandem - Provides a quick way in which to collaborate with others with minimal overhead.

Team Video - Provides an experience focused around meetings only which may or may not be what you want.

Vowel - Provides a quick way to collaborate with fellow colleagues in addition to presenting, sharing, and even transcribing audio into text.

Wire - Provides a secure platform for team communication which builds in text messaging plus video/audio calls. If you are looking for a solution focused on security, this could be a good option.

Gather - Provides an entirely unique virtual space to gather using Japanese Role-Playing Game style graphics, controls, and environment. Great for groups, hosting conferences, and/or creating unique experiences and fun environments to collaborate in.

Orbital - Provides similar features and experiences to Gather and Remo in which you have virtual rooms you can move around in. Proximity to others improves the quality of audio while moving away degrades audio. You can share video, presentations, and more in these group settings as well.

Remo - Built for larger virtual audiences and conferencing purposes and works well in a larger virtual event setting but not quite in the webinar space.

Crowdcast - Crowdcast is not as fully fledged as Hopin feature-wise but still a good choice in wanting to host a live virtual event.

Hopin - A full fledged online platform for virtual events and conferences with a bunch of great features for making a pleasant experience.

Rally - Provides virtual conversation rooms grouped as squares in which you can bounce around.

Screen - Developed by the same people who made Screenhero before Slack bought them out and destroyed the service. If you are looking for a similer Screenhere experience, this might be worth a try.

Tuple - Provides collaboration via screen sharing and multiple cursor mouse control for two people only.

Drovio - Provides another remote pairing and collaboration tool with multiple cursor mouse control much like Tuple but with support for Linux platforms too.