At a small island airport like ACK, the choice between a taxi and a private transfer comes down to one thing: how much do you want to leave to chance during a busy season?
Taking a taxi
Taxis wait outside the terminal. For most of the year, getting one is straightforward — walk out, get in, go. The ride to town is 10 minutes and costs $15-$20.
The problem arises during peak summer. Nantucket has a small fleet of taxis, and when three or four flights land within the same hour on a Friday afternoon in July, the taxis fill up fast. You might wait 15-30 minutes for the next available one. It is not a crisis, but it is an inconvenience when you are ready to start your vacation.
Taxi vehicles on Nantucket are generally well-maintained. Drivers know the island. The experience is fine — the only variable is availability.
Booking a private transfer
A pre-booked transfer means a driver is there when you arrive, regardless of how many other flights have landed. You specified your flight details at booking, so the driver times the pickup accordingly.
The cost is higher — $25-$45 to town versus $15-$20 for a taxi. For that premium, you get certainty. If you are heading to a rental home in Madaket or Siasconset, the value increases because taxis heading to those further destinations are even less available during peak times.
Key differences
Availability: Taxis are first-come-first-served. Transfers are reserved for you. In summer, this distinction matters.
Cost: Taxis are cheaper by $10-$25 depending on destination. For a solo traveler on a budget, that matters. For a family of four, it is negligible.
Vehicle choice: With a transfer, you know what vehicle is coming — important if you have multiple bags, car seats, or surf gear. With a taxi, you take what is available.
Off-season: In the quieter months, taxis are almost always available and the price difference is harder to justify. A transfer still makes sense for last-flight-of-the-day arrivals when taxi coverage thins out.
The Nantucket-specific factor
Nantucket is an island with finite resources. There are only so many taxis, only so many drivers. This is not a mainland city where supply scales with demand. On a busy summer Saturday, the island's entire taxi fleet can be occupied. That reality makes pre-booking more valuable here than at most airports of this size.
Recommendation
If you are visiting Nantucket between June and September, especially on weekends, a pre-booked transfer saves you from the one friction point in what is otherwise a very easy airport experience. In the off-season, a taxi works well for most situations.