depends upon the rest of your system. but, wilson seems to like & pair well with higher end transparent cables. i'm not sure how they perform with other networked cables.
I like the Nordost/Watt Puppy combo with Levinson electronics and front end. I started with MIT but when I upgraded I auditioned 2nd from the top MIT with the top Nordost speaker cable and felt Nordost delivered a slightly cleaner bottom end. It is also much easier to install (no huge boxes) and cheaper as well.
Without a doubt, Transparent Refence XL cables. The speakers are internally wired with them and I have never heard anyhting that has the control that these cables have.
I agree with JTINN, that the Transparent Reference (or Reference XL) is excellent with the Watt/Puppies. I have used the Reference on my Wilsons for five years and there is nothing even close to them. I am presently running Krell 650MC's from the KPS-25SC playback unit and can't think of anything better.
I'll share my past experiences with getting the performance I wanted out from my Watt3/Puppy2. I'll jump to the bottom line - get Bybee'd first before spending a ton of time and money on speaker cables. If you then want to go further from that point there is additional musical improvement with better cables, but realize the biggest bang for the buck from where you starting from is Bybee. Now my puppy's tale. I've owned these speakers for more than 7-8 years. I was a very serious Crosby/Quad owner before that, and with big electrostatic bias I do expect an intimate musical experience from my system. The Crosby/Quad give you that but they never rocked or sounded real or full bodied on big classical pieces. I went the Wilson route and that's different story so back to your question about cables for Wilsons. I've done MIT and Transparent from the amp to the speaker and the Puppy Tails. The Transparent Reference (I am sure XL is fine also) was better. Big Dynamics, tight control, great bass and pretty damn good as Jtinn notes. Maybe that is what you are looking for and Transparent delivers on that in spades. Still it sound to me that it was not quite as musical. I started experimenting with various Puppy tails from different manufacturers and also using them as short speaker cable runs from the amp. BTW I still think that Nordost SPM and Alpha-core AG-3 produced better results for me than the Transparent Reference. Then I got an Audio Note Ankaru Mono Amps with some Audio Note SPz speaker cables. Physically, they don't look stand a chance compared to the others, but immediately they produced the best over all musical experience for me. Fast micro and macro dynamics but not over controlled. Timber, tonality and musical rhythms were right. Male and female voices were both as they should be. The music sounded more natural and coherent to me. My cmusic-buff friends agreed. A close friend of mine and of Jack Bybee recommended Bybee components and things got way better immediately. Then JB and LN said lets wire the speakers internally with AN SPz and with Bybee components (specially designed) to each driver. I did that. Wow, these Wilson watt3/puupy2 started to sing. I then internally Bybee'd every component input and output in my system. It is now so open, fast, natural, coherently musically intimate that I have been listening for many more hours a week in the two years without another major article change in the system. There's a lot of great music in Wilson's as they are, but there is more music to be harvested from these speakers. Much more than switching to newer or different models. I hope this helps you a bit. Have fun and let us know about your journey.