Best phone for blind and visually impaired

Dear readers, I am a student in Product Design in The Netherlands. At this moment I am researching mobile communication needs for blind and visually impaired for my university. I am already surprised by what I have read the last days. People using Twitter and Facebook. I am wondering what apps you use and social networks. I also wonder what hardware you prefer. Is the Ipad really a miracle for blind and visually impaired people? Thanks for helping me.