What's better, Alexa or Siri? Trick question! For most of the world, there is no Alexa.
Imagine if, on a weekly basis, you saw or heard "Xinghua" being compared to Siri. But "Xinghua" was available only in China and only to people who spoke Mandarin. How meaningful would those comparisons really be to you in the U.S.? That's about as meaningful as headlines comparing Amazon's virtual assistant, Alexa to Apple's Siri are to the vast majority of the world's population.
The one vs. the many
Right now Alexa is solving only for people in America who speak English. That's an incredibly small subset of what Siri, which just recently added Hebrew and several other languages in several other reasons, solves for.
What's more, Alexa only exists in the living room at home. Siri is in the living room on Apple TV, but also in your hands with iPad, in your pocket with iPhone, and on your wrist with Apple Watch.
If I ask Alexa to turn off my lights, well, nothing happens because I'm in Canada and Alexa doesn't officially exist here. If I ask Siri, the lights go out. And if I ask Siri while I'm out of the house but have my phone with me., chances are they'll go out as well. (Networking is hard.)
If I speak French to Alexa, it might as well not exist even in America. If speak French to Siri, it answers just fine. Now, I can even speak French and ask for an English movie, and Siri on Apple TV can figure out not only the language I'm speaking, but that I'm changing languages mid-sentence, and handle it appropriately.
I can also travel with Siri, and use the assistant I'm familiar with, on the devices I have with me, in many places around the world. It's not stuck at home. In a U.S. home. With constant power. And multiple beamforming mics.
Alexa certainly is good and useful technology, and I applaud Amazon for taking the lead in home hubs and providing a way for other services to hook into it. I hope Apple does both those things in the near future.
Natural language, sequential inference, and voice interface are incredibly enabling technologies, including and especially when it comes to accessibility and inclusivity. We need them everywhere.
That's why, for now, there's no comparison between Alexa and Siri. Or rather, any comparison is laughably U.S.-centric. For the rest of the world, it's not that Alexa isn't even close. It's that Alexa isn't even in the game.