May has to be my favourite because of her character development throughout the Hoenn season, she changed like a normal person would, it was more of a realistic character for me. Misty I did like, in fact, I adored her at one point to the area were I wanted to be Misty, but after watching the Pokemon Series again, I watched May's progress throughout it and saw her be the one who only wanted a Pokemon just to travel for her own needs to become someone who became a brilliant Pokemon co-ordinator. She was a intelligent character too yet was pretty fun with large ambitions. She after that became the character I wanted to be more than I did Misty.
Misty. I did like her personality, she was the strong, caring tomboy who I could relate to being like myself in certain aspects. But to me she was a sideline protagonist who never really showed much, she always seemed more of a comic relief type character to me, it was like have Brock doubled at times. The whole "She was the original protagonist she is the only one who could ever be there" isn't what I believe, the more developed ones are better to me as it is developed, basically, added more onto it making it more entertaining. The originals are good, but moving on is good too.
Dawn, eh, I never liked her as much as the other two. She seemed to be too predictable compared to Misty's unpredictable personality and May's wild ambition that could have turned at any points. If they had given her something unique like the other two and less girly, I would have liked Dawn more. Sinnoh never did seem to gain my attention as much as Hoenn and Kanto/Jonto did.
Iris hasn't been shown enough for me to put as a favourite neither as a one I dislike, more episodes are needed for this, but so far I'm enjoying her character.