Protagonist or Nemesis – How to choose?

My little witchies are taking shape, but I find the one I intended to be my protagonist is just as vague and nebulous as ever. I am finding her quasi-nemesis a much stronger character who is easier to write but not at all the direction I wanted to go in with the story. I can’t seem to get a good handle on my intended heroine, I can’t seem to nail down a personality for her. The other one sort of showed up in my head fully-formed, but I am struggling to construct this character. If I shift to the nemesis as my main character, I think she’ll need some revision to take the spotlight. As Jane Austen said about her character, “Emma”, she’s a character “whom nobody but myself will much like.” I don’t know whether to try to make her more likeable, or keep trying to solidify the intended heroine. I think she needs to be in the story to move some things along, so writing her out I don’t think would help. I’ve tried doing those profile lists where you pick a bunch of characteristics and make up a background and personality but always found them tedious. Maybe I should just go with the nemesis for now, flesh her out more and see where it leads. Hopefully my hesitant heroine will materialize a little more fully down the road.