I think its just a matter of preference.

Bora Bora is more convenient. You can to and from the main island form the motu resorts pretty easily. There is more to do in terms of activities, and yes you can visit other islands too. I have to agree that French Polynesian service is not as good as you would expect, not as good as SE Asia. Its just easier to get around, and to and from the airport also in Bora Bora.

The Maldives is stunning, but as others have said, you need to be willing to stay on your island resort and go no where else during your trip. Also depending on which resort you end up choosing many resorts in the Maldives are located far out enough where you are required to overnight in Male either on the arrival or departure. Your flight might arrive late after dark or depart early i the morning before or after the seplanes fly for the hotel transfers.

You can't go wrong with either, but I just think Bora Bora is a little more convenient.