Your question is very difficult to answer. Every single person that responds will give you a different answer. Thats OK. We all have to make out own decisions on how we choose our audio components. This is how I do it.
I feel the best way to pick the best cables for your system is to properly match your components. Cables do make a difference but I feel that most audiophiles have unrealistic expectations when it comes to cables. They ask too much. Every time I try a cable that makes a "big" difference, even if I like them at first, almost always fail over long term listening. In my system, I don't want cables that make a big difference.
Also, people always try to use cables to fix problems in their system. For example, a very common complaint is high frequencies can be too harsh or bright. In that case, the real problem may be a metal tweeter. I feel the best way to fix this would be to get a speaker that has a soft dome tweeter. Many people would not agree with me and buy cables (and sometimes tubes) to fix the problem. This almost never works.
In the end, if you match your components properly, you only need to buy cables to do what they are meant to do in the first place; transfer the signal to the next component. Doing it this way makes it very easy to choose cables. Not only that, you'll save a lot of money.
