Testing shows Siri beating out Google Now and Cortana for accuracy, user satisfaction and more

Siri received high marks from users for answering the questions. For example, when the three assistants were asked the question about who won the Super Bowl in 1978, Siri answered correctly 95.3% of the time. 86.1% of users were satisfied with the response. While Google Now had the correct answer 88% of the time, 80% of the time it responded with a web search. Cortana gave the wrong answer 3.3% of the time.
Overall, Siri had the fewest incorrect answers (2.4%), the highest number of satisfied users (81%), the lowest number of follow-up questions (5.2%) and was tied with Google Now for having the lowest percentage of answers that were in the form of a web search (5%). Google Now was second in the test, with Cortana third. Google Now (68%) and Cortana (57%) had low satisfaction scores compared to Siri, which has to be concerning for Google and Microsoft.
Interestingly, those living in the Western states gave higher satisfaction scores to Siri, while those living in the East gave higher satisfaction scores to Google Now and Cortana. Additionally, women using Cortana and Google Now received follow-up questions twice as often as men. This might have to do with the way that women using the two personal assistants structured their questions and task requests. Siri, on the other hand, asked follow-up questions of men more often than women.
source: ExpertsExchange via WMPoweruser