I use the Garmin more but I have used the Iphone. The Iphone tends to be "Very" generous on Segments and elevations as does Android. The advantage to the phone is you can send to Strava before you get home. The Advantage to the Garmin is you can update to Ridwithgps and Mapmyride plus Garmin Connect. You can then program a ride on your computer and save it to Garmin as a course and follow the turn by turn on a ride. Haven't tried that on my phone.