So I had to do it. I went and bought all three smart speakers and tested them out to see what the difference was and if there was a distinct winner. Here are my results:
The homepod has the best sound quality out of the three in the sense that it isn't directional but rather features 360 sound and scans the room to optimize the wavelengths.
The Echo had the best technology and functionality system. Regardless of how far away I was the microphone could detect my name, regardless of the question (for the most part) Alexa seemed to be able to accomplish the task, and it just worked seamlessly especially when setting up.
The Sonos was fairly simple to set up but the microphone was awful in detecting your voice and the sound was good but not great. Neither the Echo nor the Sonos featured 360 sound so that was unfortunate..
Overall I think if you are not looking for anything crazy or real quality audio but more of an actual smart speaker assistant, then Echo is the way to go. If you're looking for better sound, then go with either the Homepod or the Sonos.
Design wise, the Echo and the Sonos were ugly, the homepod was decent. Nothing too crazy..