Belial the Worthless
I'm hoping that White ends up as bad a** as she looks. I'll ship that.
Except for the part where she won't be in the anime.
crying I wanted to see her so badly!
I would say Misty. No, not because, "She was first!11!1" like so many other people are saying, but because of the hints. To be honest, I stopped watching the anime somewhere in Johto. Not because "Misty left! *emo whine cry*" but because I just didn't wake up to watch it anymore. I'll watch Pokemon occasionally now, but only where there's an episode I want to see online (like where Ash crossdresses).
I'll start of by why not the other girls.
Why not May? Because even when one rarely catches an episode as I have, one can still see how ContestShipping is probably supposed to be canon. Also, most of the "hints" on Bulbapedia could be constituted as friendship (as 90% on practically all hints on Pokemon are besides the onsided canon ships).
Why not (insert oneshot character here)? Because a single meeting does not equal a good relationship.
Why not Dawn? To be honest, I have little against Dawn. Pearlshipping seems way more plausible than Ikarishipping. Still, their relationship seems more like brother and sister to me than anything. (actually, I like Twinleafshipping, mostly because of the game)
Why Misty? There are several hints towards Misty's feelings towards Ash in both the movies, the manga (EToP), the rest of the anime. The question here is more like, did she get over Ash and fall for Tracy, or does/did Ash ever return her feelings? Although 4Kids is made up of Pokeshippers (hence the changes in the dub), there were quite a few hints in the Japanese, mostly in the second movie.
Personally, whom ever Ash ends up with, I don't mind so long as it is reasonably hinted at. He probably won't end up with anyone seeing as the show will probably go on as long as the games do.