For me:

• Awesome stickers with very good custom sticker support.
• You can use a nickname to chat, you don’t need to share your GSM number with anyone which was an incredibly stupid idea in the first place. On that account , better privacy than Signal or ShitsApp.
• You can use simultaneously on multiple web AND mobile devices.
• You don’t lose your chat history when you login from another mobile device like in ShitsApp.
• Stores your media server-side. So you always have your full chat with all the media in it. Of course this requires care about what you share with other.
• Forwarding messages between chats has a lot of flexibility.
• Constantly improved. They are always adding more features.
• The channel support is really good…