At a small airport like FNI, the question is less about which option is better and more about which option will actually be available when you land.
Taxis at FNI
A few taxis usually wait outside the terminal when flights arrive. They are metered, regulated, and the drivers know the area well. For a ride to Nîmes center, expect to pay 30 to 45 EUR.
The catch: FNI handles very few flights. If multiple passengers want taxis from the same arrival, there may not be enough to go around. During summer, when the airport is busiest, this can mean a wait. In winter, there might only be one or two taxis at the stand.
Taxis work best for solo travelers or couples heading to Nîmes proper. If you are going further afield — Avignon, Arles, the Camargue — the fare gets expensive, and you are relying on a driver being willing to make a long trip.
Private transfers
A pre-booked transfer guarantees a car is waiting for you, regardless of how many other passengers need rides. The driver tracks your flight and adjusts for delays. The price is set when you book.
For Nîmes center, the cost is 40 to 65 EUR — about 10 to 20 EUR more than a taxi. For that premium, you get certainty. No wondering if there will be a taxi. No meter running if there is unexpected traffic.
Where transfers really make sense is for longer journeys. If you are heading to Avignon, Uzès, or somewhere in the Camargue, a transfer at a fixed price is more predictable than a metered taxi covering 50+ km.
What about the shuttle?
The shuttle bus (6 to 9 EUR) is the budget option, but it only runs for scheduled Ryanair flights and only goes to Nîmes station. If that works for you, it is the cheapest choice by far. But it does not serve other destinations and may not wait for delayed flights.
The practical recommendation
For Nîmes center on a budget: take the shuttle if the timing works, or grab a taxi.
For Nîmes center with peace of mind: a private transfer is a modest upgrade that removes the "will there be a taxi" question.
For anywhere outside Nîmes: book a transfer. The fixed price and guaranteed vehicle make the longer journey much less stressful than hoping a taxi driver is willing to go to your exact destination in the Camargue.
For groups of 4 or more: a transfer minivan is likely more economical per person than separate taxis, and you all travel together.