If I was a newbie and had no money to spend I would choose between MeetingBurner and A Google hangout.
Google hangout because you can create an event and invite people and they never have to leave google+. So it is less for Google+ users to actually do.
MeetingBurner because the basic webinar registration page seems the easiest to setup and seemed to convert better. At least for me. Plus it emails them the reminders and you have the option to export the registrants later if you get a email service like aweber.
I am defintitely looking at using group skype for my webinars in the future. Seems like it would be more personal. I have only ever used it for one on one. But for groups it is not free. You have to pay for a business account. And setting up a “skype group” optin page is a bit “techy” so it is probably not that great for the beginner. But as soon as I do one and try it out I will post the results here either way