Project Treble support on the Samsung Galaxy S9 and S9+ ensures that both devices are able to run fully-loaded AOSP ROMs without any issues. Stock Android on Samsung hardware, surely life doesn't get much better than that?
https://www.notebookcheck.net/The-Samsung-Galaxy-S9-running-on-stock-Android-gives-users-the-best-of-both-worlds.289858.0.html