For Smart phones, last time I checked what my blind friends were using they said the best thing at the time was a specialized operating system and app for a Nokia phone and it worked really well. But they also said iOS was improving fast and that several years ago.
For dumbphones it's a lot easier, you can get fairly easy to use talking phones, check what the associations for the blind recommend now. Or check http://www.blindbargains.com/
For desktops and laptops I think Windows is still ahead a little because the software packages available for it, JAWS and WindowEyes are built for it and have been around a long time. The learning curve is so steep for them though that they said unless you needed windows, then apple with it's built in, free, screen reader was a cheaper and almost as good option and a lot of blind people do use it.