Well I say I've made my point with how much I think Sari is amazing, despite her lack of techniques, if everyone was a level 1, she'd nearly quadrouple their hp and strength.
Second was a little tough, I can't really go with Rune, which is quite amazing since I'm usually the magic lover, but he lacks in a good all around position, he focuses completely on magic. Though I like that, I couldn't accept him.
Wren, though, he is amazing for going on so far, and his skills, through lack of techniques really improve him as well as never needing to be revived outside of battle, or healed much, even with how much hp he obtains. So he's a pretty safe bet.
Now, if I were forming a team, my next choice would probably Raja, or Kyra, a good healer, but alone they only have a few goodies to protect themselves.
Now then I thought about Rika, one of my favorites, and a good healer and protecter, But...she has quite a few techniques and or skills to attack the enemies, not to mention her attack is reletively decent. She'd be my third.
So my votes go like this:
Sari-10 Being the all time top
Wren-9.5 He'd be a good match on his own, but most likely coudn't hold his ground against Sari
Rika-8.9 I couldn't find myself giving her the 9, mainly because a few character could beat her.
If given a 4th choice, I'd have to chose Chaz, Excellent balance character.
Left to right:

Sari

Wren

Rika