I think switching rapidly from one set to the other is the WRONG way to do it. Hook up one set and listen to it for a few hours with lots of different types of music. As someone else said, take lots of notes. Use mostly acoustic instruments and male and female vocals. Ask yourself does it sound natural, i.e. like real life? Are the dynamics lifelike? Can you listen for hours without fatigue? Listen to solo guitar. You should be able to hear the sharp attack of the pick on the string as well as the note. Strings should sound resonant and non-screechy. Trumpets and trombones should sound warm and full sounding, not pinched and small. You should be able to hear lots of overtones on sustained piano.
Listen to bad as well as good recordings. Can you still stand to listen to the bad ones?
There are some cables (and components) that sound smooth on the first listen, but after extended listening you realize something is missing. On the other hand, some sound very exciting but ultimately are fatiguing. After you've made a first pass through each of the cables, try to rank them. Then concentrate on the top two, and listen to each for several hours. You should have an intuitive feel for which cable sounds the best.
I don't know what price range you are looking at, but, if you can arrange it, try to get some really good neutral cables to use as a reference.
