Umm... I don't really dislike May that much... I used to dislike her intently because... ; I don't really know... She replaced Misty, and she always seemed really puny and annoying to me... I also disliked her voice.
As it is, I really haven't seen that many episodes with her in, if I'm honest. I suppose I need to see more of her if I'm to form a proper opinion.
Why should a fan of Harley also be a fan of May? They are quite dissimilar characters.