Well according to the folks at Stone Temple Consulting (via The Verge), they have decided to put all three voice assistants to the test, and unsurprisingly it looks like Google Now came out on top with a score of 88%. This was followed by iOS at 53%, and then coming in third was Cortana with 40%.
According to the company, how they tested the voice assistants was by asking each service 3,000 voice queries. There were a variety of questions asked about all sorts of things, after which they tabulated the results. Given that Google is a search company at its core, it is not surprising that they managed to provide the most accurate and correct answers.
Interestingly enough it seems that when cross-checking using normal search, it turns out that using Bing provided more complete results compared to Cortana, thus indicating that Microsoft might have more work ahead of them to better integrate Bing with the voice assistant feature, but what do you guys think?