Bogotá in notorious for the security of its taxis. The latest murder of a DEA agent in a taxi has made taxi safety an even more frequent topic among both locals and internationals. So, it is important to not hail taxis from the street.
I use a company called Táximo. They have rigorously screened drivers who are super professional. Some even speak perfect English! I use them for airport pickups, city tours for visiting family, and trips outside of the city.
For travelers, they have a temporary membership card. All you need to do is call or make a reservation online and they'll send you a temporary card on your first ride. You can load up the card with 30,000 pesos which is basically the cost of the airport ride. Check it out http://taximo.co/