Some good stuff with Discord... Persistent, and you can have multiple channels, for different games etc, and can create separate vopice-channels if the GM need to talk in private with a player. You can access it on many different devices, both phones and computers. You can upload images, have bots for dicerolling. Also rather good voice. video was not so good when we tried it though, but if it is your regular group then that might not be so important..