Definitely the HomePod. I think to really take advantage of the AirPower, one would have to own the Series 3 Apple Watch, latest AirPod battery charging case and of course the iPhone X/8. Wireless charging is a nice convenience, but the HomePod is a completely different experience being offered.
If somebody wants truly an audio experience, I think the HomePod will deliver that. And of course it will integrate with other iOS devices as well with the continuation of Siri enhancements.
Hm, tough one. Air thingy I have no need for, and the HomePod night be inferior in terms of audio even to an iPod HiFi. Will have to see - and hear - once released but not holding my breath