Wellington is a small city with a close airport, so the difference between a taxi and a private transfer is less dramatic than at many international airports. Still, there are situations where one makes more sense than the other.
Price
Taxis are metered and cost NZD 30-45 to central Wellington. Private transfers run NZD 35-60 for a standard sedan. The price difference is minimal. The taxi rate depends on traffic and exact destination, while the transfer price is fixed at booking. For short rides like this, the financial difference rarely exceeds NZD 10-15 either way.
Availability
Taxis are usually available at the rank outside arrivals during normal operating hours. Wellington Airport does not run flights overnight, so the very late scenario is less extreme here than at 24-hour airports. Still, during the evening hours (after 20:00) and for delayed flights, the taxi rank can thin out. A pre-booked transfer guarantees someone is there.
The ride-hailing factor
Uber and Ola add a third option that blurs the taxi-vs-transfer comparison. Prices are often between the two, and the experience is similar to a transfer (you know the car, the driver, the price estimate). The downside is surge pricing during peak times and the occasional wait for a driver.
Comfort and certainty
Wellington taxis are generally well-maintained and drivers are professional. You will not encounter the quality variation that plagues taxi ranks at some airports. A private transfer offers a slightly more polished experience: a named driver, a specific vehicle, meet-and-greet at arrivals. For a 15-minute ride, this may or may not matter to you.
Payment
Both options accept card payment. Wellington taxis have been card-friendly for years. No need to worry about carrying cash for either option.
When to choose what
A taxi makes sense when you arrive during the day, travel light, and do not mind queuing briefly at the rank. A private transfer makes sense when you want certainty (especially for evening arrivals), are traveling with family, need a child seat, or have heavy luggage that requires a specific vehicle size. Given the similar pricing, the choice often comes down to whether you prefer the simplicity of walking to a taxi rank or the predictability of a driver waiting with your name.