As Android, does not provide anything else than Hangout on the new nexuses for SMS this is the original alternative.
Do not hesitate to report any issue by leaving a 5 stars comment !
Source code : https://github.com/slvn/android-aosp-mms
Interested in beta version ?
- Join this community : https://plus.google.com/communities/116458022649785714772
- Accept the beta test : https://play.google.com/apps/testing/fr.slvn.mms
- Wait for the store to propose the beta.