Once you get past the fact that any data you don't explicitly control is by definition not private, the next conversation is about how much you are able to trust a particular company with the data they collect, and that is really an individuals choice.

Niven stuff like iCloud leaks, and Apple bending over to appease China by removing the protest app from the app store (which completely makes it unable to be installed on any non jailbroken device btw), I personally don't really see a reason to trust them any more than Facebook or Google.