Siri has a huge latency problem. I say "Hey Siri" and its' precious seconds before she's listening (articles online tell us that it's possible to just ask the entire question without waiting for the beep -- but doesn't work, sometimes Siri's just not ready.). Someone at Apple clearly needs to reengineer Siri -- I say this as someone who's bought into the Apple ecosystem.

Siri is the like the Apple Maps of voice assistants.

Alexa (at least Echo gen 3) doesn't have this delay. I can talk with Alexa without getting frustrated at the latency. (unfortunately Alexa doesn't handle pauses or stumbles in sentences well)