As an Android user, I've found that Siri tends to be generally better than Google Now. I don't usually ask my phone for trivia, but rather to do something. Most of the time I'll get routed to a search query when I'm looking to command the phone instead. This is somewhat frustrating if you don't know the magic incantation to make Google Now do what you are asking it to do. Siri's engineers have done a better job antic…
When Siri fails for me, I sometimes ask my 7 year old to talk the same thing to Siri and she gets better results. My daughter has a more 'American' accent than me so I have concluded that Android is better at hearing through accents than iOS.
(I haven't yet read the original article but wanted to quickly comment since our observations are completely opposite)
EDIT - iOS tablet user = iPad user.