Both options will get you from Trivandrum Airport to your destination. The question is which one fits your situation better. Here is a straightforward comparison.
Prepaid Taxi at TRV
The prepaid taxi counter is just outside the arrivals exit. You tell them your destination, pay the fixed fare, get a receipt, and walk to the assigned car. The system works well and removes the haggling that plagues regular taxi stands in India.
The cars are generally older model sedans, usually Maruti Suzuki Dzire or similar. Air conditioning is standard but not always powerful. Drivers are registered with the airport authority, which adds a layer of accountability.
The downside is that during busy arrival periods, you may wait 15-20 minutes for a car. The vehicles are functional but not luxurious. If you have more than two large suitcases, space can be tight.
Auto-Rickshaw
Auto-rickshaws are the cheapest option and are available outside the terminal. They are open-sided three-wheelers that are part of the Kerala experience. However, they are noisy, exposed to weather, and have essentially no luggage space. Drivers at airports tend to quote inflated fares to tourists.
For a solo traveler with a backpack heading to the city center during the day, an auto can be a fine choice. For almost any other scenario, it is not the best option.
Pre-Booked Private Transfer
With a pre-booked transfer, your driver is already at the airport when you land. They track your flight, so delays are not a problem. You are met in the arrivals area with a name board, helped with luggage, and walked to a clean, air-conditioned vehicle.
The cost is higher than a prepaid taxi. But you are paying for certainty: no waiting in line, no wondering about vehicle quality, no negotiation. For families, late-night arrivals, or anyone heading to Kovalam or Varkala, this convenience has real value.
When the Taxi Makes More Sense
If you are a confident traveler arriving during the day with light luggage and heading to a central city location, the prepaid taxi is perfectly adequate. It is cheaper and the distance is short enough that vehicle comfort is less of an issue.
When a Pre-Booked Transfer Makes More Sense
If you are arriving after 10 PM, traveling with children, carrying more than a couple of bags, or heading somewhere outside the city center, the pre-booked transfer earns its price. You also avoid the mental load of figuring things out in an unfamiliar environment when you are already tired from traveling.