Telegram is a cloud-based mobile and desktop messaging app with a focus on security and speed. The best part is, they have an official Linux client and you can install it from the openSUSE Software Center.
Of all the messaging applications, this one is by far my favorite and if you really care to read more you can here.
Discord is a voice and text chat for gamers. The Text chat supports inline images and videos. Voice chat includes a jitter buffer, automatic gain control, noise suppression, echo cancellation. Server-to-client communications are encrypted.
Franz is a message unification application that combines chat and messaging services into one application. Franz currently supports Slack, WhatsApp, WeChat, HipChat, Facebook Messenger, Telegram, Google Hangouts, GroupMe, Skype, Discord and many more.
Official Site and Download (AppImage for Linux)