One of the things I find most annoying with my phones is that none of them ever were easy to see in daylight sun. So that pretty much nixes them for my consideration of use as a cycling device. If I was only interested in looking at the data of my ride after the ride, then maybe a phone and app will be the thing.
The screen of all my Garmin devices can easily be seen in bright sun. Maybe with the exception of a couple nuvi's.