The main reason that we pushed to use a library for database is the fact that it let us model our objects and made CRUD easier, I had a good experience with Realm, it's really easy to set up and work, it's fast and flexible, but size of the library was an issue, it's possible to reduce APK size by splitting APKs on build target ABI but I preferred to use GreenDao because it's based on SQLite, although I think it has some disadvantages like any other libraries but it was the best option for me.
Honestly, I didn't try Room yet but with a brief look at the documents you will find it more flexible and friendly to developers, As a Google fan, I prefer to use Google guys' library! As I said before I prefer a layer over native SQLite to a whole new database library.
I will try Room in my next project and share my experience here in an update later, hope it helps.
