I prefer the stock Google messages app, but, if somebody told me that I had to choose another, it would be Textra as well.
As for launchers, I like having Google Now as the far left home screen, so Google Now launcher is my obvious choice. A close second is Action Launcher, which can also be set up to have the far left screen be Google Now cards, and, in addition to other good third party launchers, has a backup/restore feature for settings, layout, etc.