What keeps drawing me back to the pilot suicide theory is that it only takes one person (one of the two pilots) to pull it off. These other theories, involving hijacking the plane, and flying it to Asia, inevitably require a larger constellation of accomplices, and you face the questions of "Why aren't there any links between the crew or passengers to known terrorist groups? Why is there no online chatter among the jihadi groups, as there has been for other attacks?", etc.
What's more, pilot suicide is hardly unprecedented:
https://en.wikipedia.org/wiki/EgyptAir_Flight_990
