He probably found a docile emilia interesting. In every chapter, I wonder what would have happened if emilia just acted like the reincarnated emilia would? But no, she's too abused to even learn how to love and ended up directing all her frustrations to the prince which is valid.
But it still doesn't negate the fact that he stated he didn't find her attractive (I'm guessing that means her appearance) if it was the personality issue he would of stated it such a waste you have a terrible personality when you have such a beautiful appearance. Which means he actually genuinely like the reincarnated girl for her personality but I don't see how he could deal with her being emis body. Which also means if he never had an issue to begin with the appearance he is now ok with the body itself because he has a more naive soul in the body to do as he pleases which then means he wants to be in control.
Ok so I just restarted reading this and this is something I dont get. But the king said in chap 4.4 he says what his ideal type is and also stated there's no way he could find EMI attractive yet is trying very hard to flirt with the girl in emis body. Which is still not his ideal type obviously they also have a serious dislike towards each other. I'm sorry that is so illogical to me if this was a situation I was in even of the new soul that's in the lady I disliked but she had a good personality I wouldn't be able to go after her with her wearing a body of someone I don't find attractive or disliked. I wouldn't be able to get passed it. Like I'd have to find a way to move her soul into a new body cause I wouldn't be able to touch that body. Cause to me if he can look passed the body issue then that just means he was always attracted to her but hated her personality and now that it's switched he has a body he can finally touch with soul he likes in which case doesn't mean he really likes either of em