It isn't that much better than Drive though. Plus, I feel like one of Android's main features over iOS is the file system. I will say, restoring an iPhone is 1000000x better than restoring any Android phone.
This whole debate all comes down to this:
Who's services do you use more?
As far as your statement on the filesystem, how often do you feel the need to get into the filesystem?
Android falls on the belief that people actually use the file structure. Whereas Apple aims to keep everything uncluttered, when you open an App, all of your documents that pertain to that App are available to you. That's it. They aren't trying to provide file system access (beyond the obvious security reasons) simply because they want to keep everything compartmentalized. Adding app extensions was just a way to bring functionality from one app to another, that's it. Outside of development I hardly ever need access to the filesystem, and even then when you have loads of documents it's still not easy finding what you are looking for.
It's not really an argument of iCloud vs Drive, it's an argument of what do you actually use? If you use both, well, you can fall back to which features you like better. In the end it's all about how much it integrates with your workflow. I am Apple everything, it wasn't cheap, but the end result is a great ecosystem in my opinion with everything working seamlessly.
On the flipside, if you use Google everything, Android will provide you with a lot more mileage than iOS for certain.
If you use both like I do, default to the one you like best and what plays well with your other devices, such as a Samsung TV and Android, or the iPhone with Apple TV.
In my particular workflow, I keep all of my documents that I work on most in iCloud so I can have them on the go. I use Google Drive myself for collaboration projects because not everyone likes Apple's offerings.
Think "right tool for the job." It's something I've had to come to terms with in order to be a successful systems administrator. What "job" or role will this device fill? If you get an iPhone and you primarily use Google services, you'll be having a hard time and vice versa for Android and iCloud.