If you have an Apple ID, including an iTunes account, you have an iCloud account. You just have to use it. Since you can toggle each and every iCloud feature on or off on in your iPhone or iPad Settings, or your Mac System Preferences, the question then becomes, which iCloud services are you using?
Is iCloud handling your mail and syncing your contacts, calendars, reminders, Safari bookmarks, notes, Passbook passes, and other personal data? Is iCloud Drive storing your files and making them available on all your devices? Is iCloud Photo Library keeping all your photos available on every device? Is iCloud Keychain handling your passwords and credit card information? Is Find my iPhone tracking your iPhone, iPad, and/or Mac in case you lose it or it gets stolen?
Vote in the poll above and then let me know the details in the comments below. Which iCloud services are you using and why? And if you aren't using some, why not?