Apple iCloud is a natural choice for people who are already invested in the Apple ecosystem. However, iCloud may not be the best cloud storage solution for non-Apple users as it is not tightly integrated with Android or Windows devices.
The best part of using iCloud is that it is naturally integrated with macOS and iOS, and files are automatically synced and backed up (if enabled). Like Google Drive, your Apple device settings, mobile apps installed, and other Apple-specific configurations are automatically saved in your iCloud as part of the Apple service. If you're using Apple devices, you already have an iCloud account through the iTunes setup process when you activate your Apple devices. You will also use iCloud to store Notes, Pages, and Numbers documents so the contents are synced across all your devices. If you're using Apple devices, iCloud will be your best choice for your storage services.
The iCloud is the best choice for iPhone and macOS users as it plays very well with Apple devices.