Signal Desktop is pretty bad, but their Android client is top-notch. One of the best messaging apps I've ever used. It integrates with SMS seamlessly, does inline replies directly from the notification, smartwatch support, Giphy support, etc

I have also had my share of delivery problems. But I'm on iOS and there is no alternative to Signal. So I ended up using iMessages most of the time, and Signal only for confidential stuff or when the recipient is on Android.

What I want is: 1) desktop/tablet and phone message delivery, with sane notifications and reliability, 2) doesn't feed all my messages to an ad company, 3) works on my non-Apple devices (otherwise iMessage would be entirely sufficient), and 4) good enough that I can get people to switch (or transparently uses SMS, so it doesn't matter).

Signal fails 1 (the desktop app is pretty bad) and 4 (too many little problems, others won't switch). I'm starting to think Slack, of all things, might be my best solution. Really, I just want ICQ with smart phone/desktop notifications, and picture/video embedding, which doesn't seem like it should be a thing I ought to have any difficulty whatsoever tracking down in 2017.