Apple can, of course, fine tune these results, which come from its servers and not via data stored on the device. Now, if you ask Siri the same question, you'll get one of two answers: "The one you're holding" or "You're kidding, right?"
It would seem, therefore, that Siri is no longer querying for an answer, but instead using hard-coded answers back at the mother ship. Notably, since Apple used the answers it did, it won't have to change them when the iPhone 5 (or whatever) is launched.
Meanwhile, Wolfram Alpha continues to respond to the same question with its same answer: the Nokia Lumia 900, specifically, the cyan model.
For those who might be wondering what Siri says when asked what the best tablet is, Apple already has itself covered. Siri answers "The Apple iPad is the best. And that's not just my opinion."
Of course, you can only ask Siri of that on an iPhone 4S; the new iPad does not support Siri, nor do any other iDevices, at least for now.