I think Ken generally matches his costars b/c he is such a good actor and lover(lol).
It was definitely hard to decide between Ann/Ken and Aom/Ken (I excluded Janie and Ken since I didn't really watch their lakorns yet), but in the end I decided on Ken/Aom b/c they were just so endearing in Ruk Tur Took Wan. In both of their lakorns, they fall in love so naturally and the good old way, more realistic than the extremes in Oum Ruk and Sawan Bieng.