I've never understood people's fascination with this technology. A few of my friends have the Amazon version in their houses and they've demonstrated it, but I don't really find asking a device to play a song or look up something on Google so convenient, as opposed to typing it into a computer or phone. I've yet to see anyone demonstrate a compelling reason to invest in this, but tons of reasons not to do so.
I do have a friend who has a voice-control device that seems worthy. It is none of the big names, and just does one thing: it controls the lock and camera on his front door. He can tell his phone to turn on the camera so he can see who's on the doorstep, or unlock the door, or lock the door. The software is keyed to his voice - both my husband and I tried it and it ignored us - though I have no idea how good its recognition is. There's a guy at work here who sounds exactly like my friend, and I'd love to know if he could get the door to obey him.
I think that there's only one voice-controlled device that I would like to have. I'd like to be able to say, "Ok, K-9, play <insert name of any DW episode or audio here>", and have it start playing.