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Apple is an advertising company also. In addition, your buying behaviour is possible even of more interest to them than to Google since Apple needs to know what to feed you through the App Store and iTunes.
Both Google and Apple are not to be trusted in any way with you data.
yes your right, i forgot iAd's although i still think out of the two Apple can be trusted more than Google due to the real revenue being the iOS devices themselves, as you said Apple could have a vested interest because of Apps and iAds, however i don't think they would risk it for the sake of making the platform known as unsecure, where i think Google knows they are recognised as a search brand so would push ahead more.
I suppose the general consensus would be if any of our data is entirely safe in the cloud and which of the vendors can offer a guarantee of not touching user data, Im a big fan of DropBox but even they have changed their T&C to reflect exactly this discussion, the access of client data by dropbox.