I have been researching on this for a long time now. So I can share some of the other points that aren't mentioned above.
Alexa voice search results for movie titles covers more apps than the Google assistant voice remote.
Fire TV stick has playback control buttons (play, rewind, forward) whereas you need to rely on in app controls on Android TV devices.
The new live tv tab on the fire stick can be an alternative for dth provided you have an unlimited broadband connection and have the OTT subscriptions.
If there are kids too who normally watch, then the profile feature on Amazon fire TV stick, which has brilliant features like time limits, restrictions on particular apps, pin support could be a driving force towards favouring AFTV.