Google's stock Android Messages app has been consistently good for the last few years. Simple interface that doesn't try to do too much - good search functionality and a web client if you'd like to send SMS/RCS from your computer.
I generally like the app, but I find the search to be hit or miss, and it kills me that I cannot search at all in the web client. It would also be trivial for them to coordinate backups of your messages, but this functionality requires a 3rd party app.
