I have Knit Picks Harmony Interchangeables, but have decided I don't like the cables, they are too stiff.
I recently got a fixed circular needle from Knitter's Pride (Dreamz) and I LOVE them. The cable is nice and soft and doesn't curl up. I think I will look into those next. I hear their Karbonz are nice, too, but I really like wooden needles best so far.