No offense....but you could work for their marketing team.
You already seem to know that the HomePod is the best smart speaker available, and you refer to the iPhone as a better alternative to Alexa.
A smart speaker is suppose to combine smarts and sound...that is the simple equation.
The Homepod looks to emphaize sound, because it is far behind in smarts.
Again, you already seem to know without having the device, but I have little doubt it will sound better than anything Amazon makes, and marginally better than the Google Max in a much more compact package (though it may not get as loud, that extra power/weight will amount to something).
For someone who isn't completely ingrained in the Apple ecosystem, like myself (I own an Apple tv 4k, apple watch 3, iphone x, ipad pro...but I also have a nest, nest cam, fire tv, roku, windows pc and laptop, a wife who uses android, etc)...if you want really good sound and equally good smarts, I would recommend the Sonos One bundle. From what I have read, a single Sonos one keeps pace with the Homepod (keeps pace, meaning it sounds marginally worse), but a pair in stereo mode is likely to far outclase the homepod. I am testing out a pair as we speak, and the stereo pairing really adds to the sound scene, making my google home seem pedistrian. On top of that, I can use Alexa to do anything I need a smart speaker to do (including control my home), and the Sonos app supports Apple music, etc (I have apple music, google play music, and amazon music unlimited). Airplay 2 is coming to the sonos as well.
For someone 100% ingrain into Apple, who will pay whatever appls wants and not consider the competition/possibily of merging ecosystems...the homepod is your best bet.
Also, Sonos will soon support Google Assitant as well.