Of all 3, I'd say Alexa is the most practical for using at home, google one is kinda the smartest one but also is the most frustrating one - what worked yesterday will not work today or will work occasionally (exact same prompt's wording). Siri will not always respond but overall works fine within its somewhat limited scope, as compared to others (like number of integrations supported), but then again - ecosystem..
My biggest issue with Siri is intercom: at home we mostly speak other language than english, and when using intercom Siri often tries to parse what's being recorded, instead of just recording audio sample and send it verbatim.
Something like:
Me - Hey Siri, Intercom
Siri - intercom chime (not 'Aha?' of responding to just Hey Siri)
Me - *bjlkabdgkjhqwruo;fghnasd.mkfnlkjashfjkasdngjkasbdg* (doesn't matter, different language)
Siri (thinking she recognized some word) - Here are the results for what you asked..
