I'd say Skype to be honest. Teamspeak is just talking, and it takes a lot more work to create your own TeamSpeak server than it was to create a Skype group call. With Skype, you were able to do more than that. You were able to video chat, have a more personalized about you page, and it has a free mobile application, etc. On the downside, Skype uses a lot of bandwidth. It is expected a bit though, but they, and you, can definitely try to fix that issue if they or you haven't already. If this was a general opinion on which platform is the best, I would probably say discord since I'm more familiar and used to the app.