The tour we took was a free tour, the "Colombian Conflict Tour: War, Drug Trafficking and Peace." Our tour guide was Natalia and she was amazing - very knowledgeable about Colombia's political history - she was able to answer every question that was thrown at her - and very friendly and helpful. I learned so much. It was perfect for me.
I will add, though, that this tour covers the history of Colombia - not just Bogota. I've taken other tours of Bogota, and they involved going somewhere and then the guide tells you what historical thing happened in that location. Since the events that this tour covers happened all over the country, there's much less of that.
For me, that was fine. I learned so much, and I'm very happy that I took this tour. I highly recommend this tour for people looking to understand how Colombia came to be what it is today.