I have used the Dropbox Datastore (deprecated), Parse, SQLite, CloudKit, FireBase, and probably others, and nothing has compared to how elegant Realm is.

- The code is intuitive and beautiful

- The sync platform is crazy-fast and reliable

- Offline-first is exactly what I need

- Queries are mind-blowingly quick (even with tens of thousands of records)

- Sync listeners are very simple to set up

- Setting up the Realm Object Server on a Digital Ocean Ubuntu VPS takes less than five minutes

I really couldn't be more impressed. I love Realm to bits (heh).