I have had Cardas GC, Cardas GR, various Transparent, Nordost Valhalla, Audinece AU24, various synergistic references and analysis plus in the past. By far the best I have heard is the sterovox cable. Its ultra quiet like Transparent, soundstages like Valhalla, and yet is smooth as silk. I would not recommend it on every system (well it also costs a small fortune), you your would really benefit from it, and you've obv already investsed quite a bit.
I have heard really nice things about Purist Audio cables, but never owned them (also expensive).
Of course everyone is going to tell you that what they own is best - so take it all with a grain of salt. But, I do think you owe it to yourself to at least audition some (any) really high end cables, IMHO. You might be surprised