[mikelehen]

This is a big question, and I'm biased by working at Firebase, so I'd welcome somebody from the community chiming in with their experiences. But one key differentiator worth mentioning is the realtime aspect of Firebase.

We believe that modern apps should be client-side apps that update in realtime as changes happen, without having to refresh the page or continually poll the server for updates. So this is baked into the core of Firebase. All of our features and APIs (and our new Hosting service!) were designed around this concept of how modern apps should be built.