https://loupventures.com/annual-smart-speaker-iq-test/
Google Assistant was able to answer 88% of them correctly vs. Siri at 75%, Alexa at 73%, and Cortana at 63%
Over a 12-month period, Google Home improved by 7 percentage points, Echo by 9 points, Siri (9-month) by 22 points, and Cortana by 7 points