It's more complicated. Apple's position as a hardware company that sells them with very good software is certainly the better position in comparison to Google, Microsoft & co.
Siri (as well as several other similar products) is based on Nuance technologies (speech recognition, text-to-speech, etc). It was recently in the news that Nuance outsourced their voice technology quality control (US based human workers listen to your voice data and checks the speech recognition quality, some workers mentioned they recognized single persons from reoccurring voice data). So your voice data is being processed by several parties.
The two big mobile OS vendors Apple and Google and also smaller players like Microsoft make it incredible hard to not-use their cloud storage&sync offering. Storage space is synthetically limited to low GB, with an high up price for additional storage. An SD-Card slot (= cheap extra storage, as a card is very cheap) is only available in Android devices (third party vendors hardware manufacturers like Samsung, Sony, etc.) but not from Google itself. All the inbuilt sync functionality only works with their own cloud storage, no third party cloud nor a simple sync over Bluetooth, Wifi or USB-cable. They could do better.