I won't touch signal because I care about user freedom more than privacy. (Both are important) No 3rd party clients, mandatory updates, mandatory google play services, and mobile only are all deal breakers.
> mandatory google play services Note that since a while there is also the possibility of using web sockets. But they are an extreme battery drain, and thus google services are quasi-mandatory. Telegram solves this without being a battery drain, possibly at the cost of delivering messages with a delay, but why isn't that my choice.
Whenever a few of us are sitting around in real life, and someone sends something to a group chat, all the phones on the table will buzz instantly together (iOS and Android).
And on top of that, battery usage is really low on Android. I use it a TON, and it's never in the top n apps of battery usage. Meanwhile, I can just open Snapchat once, and I lose a few percent.