There are three kinds of taxis in Bucharest:

1. -Taxis belonging to reputable companies, that charge an average fare per kilometer and use smaller Dacia or, more and more often, Skoda and Renault cars. The companies I would list here are Cobălcescu, Confort, Meridian, CrisTaxi, Speed Taxi, Leone, Pelicanul. They will charge about RON 1.39 - 1.40 / km. plus the starting, which is about one kilometer’s ride.
   

1. -Taxis belonging to expensive companies, that charge more, have bigger / better cars or simply have the same type of cars with the ones above, but charge more. I would list here Taxi Grand (Mercedes sedans only), Fly Taxi (hunchback cars only) and Class Taxi (regular Dacia sedans only). They usually charge 3.50 / km., with some variations depending on the time of the day / night when you go and on the type of car.
   

1. -Taxis that will cheat you. As simple as that, and the ways they will attempt to do so are various. Some of them imitate the logos of reputable companies. Others will write 7.50 RON / km. on their door, with the "7" so narrow that it looks like a 1. Or they will simply do something to the meter, so that it indicates more than it should; Taxi Arsenal’s cars typically parked in front of the Hilton and other top end hotels are notorious for that. They will come to you at București Nord railway station, saying the subway no longer runs, that they want to go home anyway and will give you a big discount (I have heard this so often that I wonder whom it works with), that they know a shortcut, there is no other taxi and they are your last chance on earth. Avoid them. Not being careful here can end with paying even 100 lei for a ride, and the stupid part of is that in some cases this might be legal (if they are licensed to charge RON 7.50 / km. and the Holy Cow knows how much for starting). This fake taxi occurrence is far less than what it used to be and it is diminishing, but be aware of this.
   

Apart from the above, two other operations need be listed:

1. -Black Cab is a company that ran shuttle and sedan services to and from the airport, respectively corporate transfers. They then started their own taxi service. All of their cars are black and most are Skoda Octavia or the like. Their pricing system is a bit complicated, but the average ride costs more or less RON 10 more than that on a RON 1.39 / km. car of the companies above. The price difference reflects the cleanliness of the car, the superior vehicle and the black-trouser-white-shirt driver.
   

2. -Uber, an online application with many affiliated drivers. The price for the ride is shown before confirming the ride and rides can only be booked online, by using a computer or smart phone.
   

All of the providers above have websites and applications that can be used to book their cars.