If youre looking for something more than just a group then I will recommend you join Reddit. There are lots of Bitcoin and altcoins enthusiasts there discussing on very interesting topics. You will also be getting updated there regularly there with lots of topics to engage in. If youre looking for just a group that also has a lot to offer, then you can go for Telegram. But in Telegram you wont be able to join any group without having the link to do so. Before you join a group, someone will have to give you the link to do so.