Fastest almost always means rail where rail exists. A dedicated airport express or a metro line beats road transport during any normal traffic, runs to a schedule you can plan around, and is immune to the congestion that turns airport highways into parking lots at peak times. The main exception is early morning or late night, when roads are empty and trains may not be running, which is when a taxi or ride-share genuinely wins on speed.
Comparing the four options in general terms: the train is fast, predictable, and mid-priced; the public bus is cheapest and slowest; taxis are door-to-door and priciest, with airport queues but zero navigation effort; ride-shares price between bus and taxi, sometimes with a walk to a designated pickup zone. With luggage or a group of three or four, the math shifts toward a car since the fare splits while train tickets multiply.
Decide with two data points: does a rail link exist and how close does it land to your hotel. If the station drop still leaves a long haul with suitcases, a car door-to-door may beat the faster train overall. The airport website lists every option with times and prices.