Hi Dominic,
WizIQ, OpenMeetings and Big Blue Button can all be integrated with Moodle. If you search Using Moodle you'll find discussions about them.
Personally, as a language teacher, I prefer Zorap outside Moodle.
It depends on your objectives and your institutional situation which one will be best for you. None are perfect... but a lot better than a year ago.
Cheers,
Glenys