Zoom
Zoom is more than just a meeting app. In particular they are making a focus on their new whiteboard. My favourite bit about zoom is their annotation tool which is what this video features. It is the best on the market in my opinion and I will often have it running during an in-person lesson simply because it is the best way of drawing over other things on my screen :-)
Teams
As a teacher you can get yourself a free Teams account which also means you can host a teams meeting for free. Teams is developing fast, in a number of ways it felt behind Zoom in 2021 in particular, but slowly the playing field seems to be levelling. If you are limited to the free version of Zoom and a limited meeting time then Teams could be a good solution.
Google Meet
Google Meet is very similar to Teams as one would expect and works as brilliantly. The only drawback I find is the whiteboard. In Meet, to open up a whiteboard you start a new jamboard, however this isn't automatically screen shared with other participants. This video tells you how you can start a new Meet.
Skype
Skype is a solid product, but one that I think is becoming more limited. You can make calls for free between anyone using the skype app (desktop of mobile). However, it lacks functionality of Zoom + Teams and if you were looking to contact parents I think they will find connecting to a Zoom/Teams meeting easier than a skype call.