Well, of the girls it's definitely Paine. She's foxy. Yuna's the girl next door, cute and nice. Rikku, well, she's a bit sluttish, but cute too. Paine has attitude.
And the guys... Well, there's so little info about others than Tidus or Shuin(Shuin is betterlooking btw), but Nooj, Baralai and that third guy(I think his name started with G...) are all quite ok. At least they look a lot better than Tidus. Hope they appear a lot in the game i.e. are playable characters.