Who is the best digital assistant?

Stone temple (a digital marketing company) has a study of which digital assistant attempts to answer the most questions and gets the most questions correct here. The key summary results graph is:

Summary graph from https://www.stonetemple.com/digital-personal-assistants-study/ - 

As a person in the apple ecosystem, I'm hoping apple can help Siri get better, but I also wonder if we are still so early in the technology development here, that all of these are not really very good?  Still as of today, Google smartphones seem to be the way to go to ask questions of your devices.