I certainly didn't dislike Fanny. I think she was a totally believable character in that situation at that time. She was a shy introvert who would have needed much more kindness and encouragement than she received (except from Edmund) in order to become more self-confident and assertive.
It's no wonder she adored Edmund - he was the only one who believed in her abilities, paid attention to her, and encouraged her.
But having said that, I think my favourite Austen heroines are still Anne Elliott and Elizabeth Bennett.