"I’ve compared the HomePod with both the Google Home Mini and the Amazon Echo Dot, and found that the HomePod, with its six-microphone array, performed best. The Echo Dot came in second, but the Google Home Mini wasn’t even close as far as microphone performance was concerned."
https://9to5mac.com/2018/02/11/home...-and-worst-of-apples-new-smart-speaker-video/
This is my experience, though my Dots are always hooked up to external speakers, so the audio can play louder than the Dot's external speaker.
I just don't find any of them to be as good at hearing what I say as the HomePod....it isn't even close. One night, I had trouble sleeping, so I moved to the living room and set both the HomePod and the Echo Dot to play an alarm at 7AM. At some point I went back to bed, but I could hear them when they went off. From the bedroom, I yelled to the HomePod to stop. It did on the first try even with both alarms blasting. I could still hear the Echo's alarm, so I yelled for it to stop and it continued. I then screamed, and it continued. I then walked in the hallway and yelled and it still continued. It didn't hear me until I was almost in the same room with it. Luckily, I was ready to get up!!!
For music, it is worse. At one time, I had the Dot controlling both J River Media and Plex for audio playback on my main speakers. It would never hear me over the speakers unless I moved the Dot right next to my main listening location (I actually bought another Dot because of this issue). However, the HomePod is near that same position as the original Dot and it controls audio on my main system via the AppleTV's Airplay 2 and it can hear me without any shouting.
I am not sure if you have a problem with your HomePod or if you just have the Dot closer to where you are sitting, but the Dots aren't in the same league as the HomePod when it comes to hearing over external noise like music or alarms. I have 3 Dots and that applies to all of them.