While at times, she would be very mean to Ash, whatever she said to him was usually said in a somewhat angry-yet-playful manner. Except for one instance where she said something to him, which I really didn't like (I thought the timing of that statement was rather uncalled for, given what Ash had been through).
But yeah, other than that one time, I really liked Misty. She and Ash, made a great team. And I'm not big on shipping either (besides Ash and Pikachu), so I always saw Misty as simply a great friend and companion to Ash. What everyone has been saying, the brother-sister relationship, does describe Ash and Misty's relationship quite well. Especially considering how the two argued so often. XD
I also, really like the team of Ash and May. May was a great cooridinator. And I thought she had really learned a lot from Ash, during the time she was traveling with him. I have to admit, it was great to see Ash teach someone else the proper way of catching and battling Pokemon. Hehe. XD But yeah, May was a great friend to Ash. And thankfully, overall, she wasn't that mean to Ash, and her temper wasn't as bad as Misty's either. So that part, I really liked! ^^
Even so, I think I still prefer Misty as Ash's female traveling companion. Ash, Misty, and Brock - the 3 of them traveling together is just classic. And of course, it's very nostalgic as well. So yeah, I would like to see Misty return at some point.
As for Dawn, once again, I think she is a great friend to Ash. Though, I haven't seen enough of D/P to make any kind of decision yet, on Ash's overall relationship with Dawn. So I think I'm gonna wait until CN airs more episodes, because I can't really see what Dawn's relationship with Ash is like right now.