When it comes to HomeKit Audio, there is basically Apple HomePod, Sonos, and everybody else. From a HomeKit perspective, HomePods obviously offers the tightest integration, as it can act as a HomeKit Hub and process HomeKit commands via Siri in addition to its audio functions. Sonos and other AirPlay2 speakers can also appear in the Home app, but are more limited in how HomeKit can control them.
HomePod VS Sonos
Before I got into HomeKit, I invested in a whole-house audio system using Sonos, and had ten speakers. Sonos audio sounds great and very reliably stays in sync. Once I started to get heavily into HomeKit I purchased two HomePods. Fast forward to today, and now I have seven HomePods and only have one Sonos PlayBar connected to my living room TV. That doesn't mean that the Sonos are no good, or that everybody should pick HomePod over Sonos. They both have their strengths and weaknesses:
Obviously the Apple HomePod is going to provide better integration into Apple's services, including HomeKit.
Great sound quality
Great Siri integration: The mics are so powerful, that it can hear whispers in the same room, can hear normal voice levels over loud playing music, and can hear from adjacent rooms. Tell it to play a song or a playlist, tell it to play a podcast, set multiple kitchen timers, create Reminders, ask it the weather, etc
Great HomeKit integration:
You can control your HomeKit devices using Siri Commands. This is quickly becoming my most common method of interacting with my HomeKit gear.
You can create automation to play music (or sound recordings) - for example, play an alarm sound when a motion sensor is triggered.
Acts as a HomeKit Hub and Bluetooth extender
House Intercom System
Great Integration into Apple Services, for example: Apple Music, Siri, Now Playing, Control Center, watch, iPhone Handoff, etc
Multiple Voice recognition for personalized interactions
Two models to chose from
Can only play content from Apple Music and Podcasts and via AirPlay 2 (although I have heard that Spotify is coming)
No line in jack for other audio sources
Connects over Wi-Fi only
Great sound quality
Many models to choose from, including Sound Bars, portable, etc. Even models to connect your old stereo equipment and speakers to.
Connects over Wi-Fi or Ethernet
Integrates with many online music services
Does not work with Siri
Does not work with Now Playing
Does not allow automations
Does not act as a HomeKit Hub or Bluetooth extender
I found that in the past couple of years of my use with Sonos that the quality of the Sonos app was becoming worse over time. Sonos updates their app quite a bit, sometimes once a week! It started to become a pain in the butt to have to apply all of the updates (generally speaking when the Sonos app is updated, you also have to apply that update to all of your Sonos speakers). And it was hit or miss if that update would bring improvements or bugs. Many builds became very slow and unresponsive.
For me it was a relatively easy decision: Because I started buying Sonos equipment early on, only two of my existing speakers were AirPlay 2 compatible the Sonos could directly connect to more audio sources, I pretty much only listened to Apple Music. So I would sum it up like this:
If you primarily listen to Apple Music and are an Apple-centered household, and if you are using HomeKit, go with HomePods
If you listen to many different music sources and need a wide variety of speaker types and have some Apple and some Windows and some Android, go with Sonos.
What I Use
Apple HomePods. The HomePods perform many functions: music and podcast playback, HomeKit Hub and Bluetooth extender, Siri commands for general use and HomeKit use. One other tip: I didn't pay full price for any of my HomePods. HomePods typically go on sale for $200 during the holidays, sometimes even as low as $180.
Here are some HomePod links you may find useful: