I've tried several, Zoom, Google Hangouts, and Skype.
I much prefer Skype, even though the new version is not perfect.
I like Zoom, hangouts and skype. All are good, I think its depend of the persons.
Zoom its good to meeting with more person, and you dont need to download anything. Its really easy to use. Hangouts and gmail it is very similar, but the person need an account . It is not a big problem becouse it is common to have one .