I made the switch one year ago after six years on a full Apple ecosystem and I think I'm going to stick with Android.
The integration between devices is neat but in my opinion it only makes sense if you have a full ecosystem. What I miss the most is the ability to make and receive phone calls from my MacBook Pro or from my iMac, but since I'm mainly using Windows on the latter I wouldn't profit from it even if I had an iPhone.
I missed iMessage in the first days after the switch but as I mainly use WhatsApp anyway I can't really say this is going to take me back to Apple. I found the syncing laggy, too, and I didn't like the fact that deleting conversations from a device would have no impact on the same conversation on the other devices. To be fair I have to say that the WhatsApp client for Windows 10 is horrible (but one can always use the web app, which I find to be better).
What I miss the most is the overall polish of iOS, aside from the integration: when you use an iPhone you have a coherent ensemble of well designed tools which work quietly and smoothly. Apps are solid, well done, and the UI, if a bit dull, is very well thought and precise in its design.
This is not to say that Android is bad. When you buy an iPhone or a Galaxy you are getting a premium product one way or the other. Do you like Audi, Mercedes or BMW the best? It comes down to personal preference: the all wheel drive system on one is better, but the other has better infotainment, while the other uses superior gearboxes. I couldn't care less for infotainment, but all wheel drive and gearbox are fundamental aspects when I shop for a car.
Similarly, when I bought my first iPhone and my MacBook Pro I prioritized polish and integration above all else; six years later I found myself choosing flexibility and customization over integration, and build quality and good looks of the hardware over UI polish. I find the current iPhones quite ugly, so I bought a Galaxy S8+ which gave me the added flexibility of Android (even if I miss the quality and consistency of the third-party apps of iOS) and will probably go for a Note at the next contract renewal, but I'm writing this on my shiny new full-spec iMac on which I run Windows, and tomorrow I'll be out and about with my MacBook Pro and my iPad Air.
Oh, well... and the headphone jack. I'm not trashing my perfectly fine Audi (which has got Bluetooth only for calls but not for music, so I use the aux-in TRS jack) nor my superb sounding AKG professional headphones because someone decided we could do without. I just can't see why...