For me it's Hangouts. While not perfect, I always come back to this one. I don't know why it's not more popular, and I don't know why Google didn't put more effort into refining it instead of wasting their time on Allo and Duo, the two of which combined pale in comparison to Hangouts. Hangouts: - Multi-platform: iOS, Android, and a web version for PCs > Proper tablet version (unlike Allo) > Excellent web version - supports multiple chat windows open at once - Works with any browser (unlike Allo) - Gmail integration - Proper multi device support. > No stupid limitations like one phone only. No "master" device. > No reliance on charge state of another device (unlike Whatsapp) - Independent login on any device. No text codes or QR code scanning nonsense. > As many devices logged in simultaneously as you like - Notifications work. Always. > Very fast and reliable notifications on iOS and Android (contrast with Telegram, which often takes a good 30 seconds to notify on iOS, and has issues with notifications ceasing to work after extended periods on some Android devices) ^ This is an absolutely critical one. You can have the best system in the world on paper, but if the notifications are unreliable, then it's useless (which is more or less the case with Telegram for me, at least on Android)> Notifies for EVERY message. I hate the Facebook Messenger system of only notifying for the first two (or whatever it is) messages. That's just a recipe for missed messages. That should be strictly an optional feature. - Chat history all stored in cloud > Seamless access from all devices > Fully searchable (via Gmail) > Readily exportable - No clutter, stupid gimmicks or ads (unlike Viber) - Does not require phone number > If you want anonymity, making a burner google account is easier than having spare numbers (but not as easy as something like Kik) - Hangouts apps have fast account switching, and notifiy for all accounts - Unified IM, voice and video calling experience. Why do I want this split out into separate apps? - Attractive, clean and intuitive UI. It's very easy to use, which is why I'm bewildered by the oft-repeated claim that one of Hangouts's reasons for failure was it being "too complicated" for the average person. My parents picked it up immediately, and they barely know how to switch apps in iOS. I know I'm forgetting some, but I'll add them when I remember. Areas for improvement: - notification repeat (like iMessage and Telegram) - Cannot change notification sound in iOS, but this isn't a deal breaker like it is in Skype, because the default Hangouts sound was actually designed to be audible in environments other than a completely silent room (grow a brain, Microsoft). - Mobile notifications are suppressed while web version is open, and there is a small delay between when you close the site and when mobile notifications resume. I wish there wasn't. I've missed many messages thanks to this stupid little delay. - Wish images were not compressed - Video and voice calling is buggy and unreliable in my experience. - iPad version does not support split-screen mode. Encryption/privacy? I've thought about this and concluded that I just don't care. I don't care if Google reads my messages. I'm not sending anything on Hangouts that needs end-to-end encryption. I can't control security on everyone else's devices, and encrypting the pipe between them means nothing if one of them is compromised. If anyone knows of another messaging platform that I might like based on the above, I'm all ears. Facebook and Skype seem to be the closest, but the inaudible, unchangeable notification sound makes Skype a non-starter for me, and I don't like Facebook, or their Messenger app's UI. Which is the best messaging platform in your opinion, and why?