Telegram is my favorite go-to chat. Unfortunately people are invested in their use of Facebook messenger, Line, Hangouts, etc., and you have to be where they are to chat with them. I have one guy who is only chatting on the apps I don't use: Facebook and WeChat. Sure, I might see a Facebook chat when I log in, but I don't use the apps and so it just doesn't work out well. I'm forced to use LINE but the same thing holds, I'm not logged in so semi-real-time just doesn't happen. I'll get a text message and also a Facetime message, and a Telegram message, and that is where I leave it. Even Twitter I use when I use it, not real-time, even for direct messages. I've also abandoned Gitter, possibly because of their support channel and its tone, but also because it is limited and can't really do what a full-blown chat/IM client is meant to.
Advantages of Telegram
Telegram is free and encrypted, and also has the nice distinction of a free sticker ecosystem, Telegram Native Apps, Telegram Bots, and chats can now be edited, after being sent. There are two more pretty great integrations: Trello and Github, and WordPress
Integram = Telegram + Trello + Github
Integram is a tool that can be added to groups and then has a unique link that can then grant access to Trello boards and Github repositories.
Telegram + WordPress
There are many Telegram WordPress Plugins (about 20 currently). I've not yet (as of 28 May 2016) evaluated which look useful, but several potential features immediately stand out as interesting: - Notify a Telegram Channel (or SuperGroup) of a new post on the site - Integrate with CF7 to send a message via Telegram instead, or in addition to Email - To emulate comments on a page but that would be overhead The WordPress Plugin for Telegram (see also this discussion for installation) uses the Telegram Bot system, as well as Notificaster, an already existing Telegram bot, for discussion in terms of a group, as well as a channel for public notifications (e.g., new post). This is great for announcements/posts and things like a general chat channel for a particular website. However, what about initiating private chats? That is easy in terms of 1-to-1 chatting, just add a Telegram.me address. While a supergroup (or regular group) might be used, it is probably best to keep a broadcast channel, small group, and individual telegram accounts. It really depends on the use cases what to configure. There could be a channel per site, or perhaps on the main category pages.
Signal, an Alternative/Competitor
Signal is a free and open source software designed primarily for mobile chat and voice calls. There is a Signal Chrome app that allows for computer-based use via associating with a mobile device account (the encryption keys are shared). Chat is basic, but includes images and other attachments, and of course voice is a great option. What Signal doesn't have (yet), are stickers and bots. What Telegram doesn't have (yet) is voice calls.