I depend on Google Assistant on both iPhones. Siri is getting better and I sometimes use it, but I find it convenient enough to tap the Google Assistant icon on home screen as hit the hardware home button for Siri.
I expect Apple to continue to invest a ton of money in AI, AR, etc. But, Google has some advantages: when I asked for driving directions to the DMV yesterday Google Assistant immediately warned me they were closed. I worked at Google with the Knowledge Graph, and it with superior AI really is a great competitive advantage.
That said, I am never going back to Android phones; I like iPhones and the integration with my iPad and MacBook is useful.
Best of both worlds.