What's the best CATV cable to use?

I live in an apartment where the master bedroom and the living room are the only outlets for Coax. I want to run my computer in the guest bedroom which is around 30-40 feet away. I am concerned about sacrificing speed because of the distance. I see so many prices online for different cables. Does it matter which Coax cable I use? If so, what is the best one to pick that will give me the speeds as if the computer was in the Master BR instead of the guest?