“Academic research published last week looked at the telemetry traffic sent by modern iOS and Android devices back to Apple and Google servers and found that Google collects around 20 times more telemetry data from Android devices than Apple from iOS.”
Both phones phone home on startup, while idle and when you open the settings screen. Both keep sending after you opt out, and even if you never log in. Android sends about 20 times more. Apple wins this test by being less bad, and the opt-out switch on both is decoration.