I'm surprised no one mentioned ZEL too much. Is it just me who just loves the whole Dissasociative Identity Disorder (Mulpitple presonalitites). I think my top five would be...
1. ZEL
2.Anna
3.Cain
4.Taka
5.Titania/ Julia
They're all really close though, and as previously mentioned, all the caracters are all incrediby unique. I love Anna because.... well.. whats not to love about her, she sees and hears things that aren't visible (or even existant) to the other characters but actually are 'true', it adds a bit of mystery. Cain is just really amusing, a pretty cool rival and unique as well. Taka, like others said before me, is a good guy at heart but forced to do stuff he wouldn't want to, and does so half heartedly, he even goes to the point of telling the player what else is happening so they could, of course, stop it. Titania.. well, I don't know much about her but at the Trainer School, if you read her diary(Hehhehe), it gives you a pretty good snapshot of her personality. I guess putting her name on the list is more of a place holder, but I have high hopes for her If she doesn't turn out to be as expected (Which I doubt), then I'd probably chose Julia... No explanation needed xD (Kaaa BOOOM)