We went to Moorea last summer. Our flights in and out of Papeete forced us into overnighting on Tahiti both at the start and end of the trip. Therefore, we took the ferry. It was a pleasant form of transport, and it was interesting to see local residents. We will return to Moorea this year. I plan to fly, as our flights in and out of Papeete do not require an overnight. It will take considerably less time to simply stay at the airport and fly.
Taxis are expensive in Papeete. By the time you pay for a taxi to the harbor and pay for the ferry crossing, you will not save as much as you might think, while you will spend a substantial amount of time.
On the return to Papeete, there were no waiting taxis. We had booked a car. The agency was supposed to have someone at the dock. No one was there. We finally found someone willing to place a call to Avis. They had no one to drive the car over, so my husband walked the mile or so to their office while I stayed at the harbor with our luggage.
I stayed at the Tahiti Sheraton, now Hilton, at the start of the trip, and Le Meridien at the end. Le Meridien is somewhat nicer, but neither property is a standout. I'd simply chose which ever one offers the better rate or gives a stay toward status in the program of interest to you.