QUIK SMS: Open source replacement to the stock SMS app on Android. A fork for revival of the now unmaintained QKSMS.

Other alternatives:

• Fossify SMS Messenger
• Connect You

A reason to avoid the stock SMS app on Android:

Android's Messages, Dialer apps quietly sent text, call info to Google

Google's Messages and Dialer apps for Android devices have been collecting and sending data to Google without specific notice and consent, and without offering the opportunity to opt-out, potentially in violation of Europe's data protection law.

According to a research paper, "What Data Do The Google Dialer and Messages Apps On Android Send to Google?" [PDF], by Trinity College Dublin computer science professor Douglas Leith, Google Messages (for text messaging) and Google Dialer (for phone calls) have been sending data about user communications to the Google Play Services Clearcut logger service and to Google's Firebase Analytics service.

"The data sent by Google Messages includes a hash of the message text, allowing linking of sender and receiver in a message exchange," the paper says. "The data sent by Google Dialer includes the call time and duration, again allowing linking of the two handsets engaged in a phone call. Phone numbers are also sent to Google."

The timing and duration of other user interactions with these apps has also been transmitted to Google. And Google offers no way to opt-out of this data collection.