Hm. I really dislike Google's ecosystem, so I don't think I'm interested in switching to it. And my initial experiences with hangouts were super negative.
I'm using an app (messenger?) that just puts a slightly better UI on Android texting, but it's still pretty bad. I should look into using Telegram, though.
By far the biggest gripe with texting is that it's not persistent across devices. That's a core requirement that seems like it should have been solved a decade ago.
Realistically, how would Google sync texts between devices without sending your texts to Google? And once you're doing that, why not use Hangouts, which does, in fact, do pretty good cross-device sync?
I ask as a fellow Google-avoider; I think your competing requirements are asking for an impossible thing.
Apple's iMessage does this, each device has a public/private key that is shared. When you send a message it is encrypted with all of the recipient's devices public private keys. If the device is not on at the time Apple holds on to the encrypted message but cannot read it because the private key is stored on the device. The only downside to this is that you cannot sync old messages to a new device.
I'm using an app (messenger?) that just puts a slightly better UI on Android texting, but it's still pretty bad. I should look into using Telegram, though.
By far the biggest gripe with texting is that it's not persistent across devices. That's a core requirement that seems like it should have been solved a decade ago.