In January 2014, WebAIM conducted a survey of preferences of screen reader users. We received 1465 valid responses to this survey. This was a follow-up survey to the original WebAIM Screen Reader User Survey of January 2009 and the follow-up surveys from October 2009, December 2010, and May 2012.

Read more at
http://webaim.org/projects/screenreadersurvey5/