I haven't used an iPhone in a while, does Siri have a wake word? Does it work when the phone is in standby? Android has "Ok Google" but it doesn't work when in standby and doesn't work from the distance that Echo does.

I think that's really its killer feature. You are in the pantry and notice you're out of basil, you say "Alexa, add basil to my shopping list" and it's done. No pulling out your phone, no unlock screens, you just say what you want to happen and it works.