The top reason was actually an issue with the Android experience.
Over 53% of respondents said they moved to iPhone because of
problems with their Android smartphone. Specifics cited were
“their old phone did not serve them, because it was aging, needed
repair, or had some deficiency that affected their user
experience.” The second most common reason to switch was for new
features on iPhone like “a better camera, enhanced accessory
options, or a more intuitive user interface.” [...]
Finally, just 6% of those who switched from Android to iPhone said
they made the move because of iMessage and FaceTime.