I actually LOVED the main characters in this one. I'd rank them probably behind 6, and 7's characters, but I'm not sure there is another game I'd put above them.

Auron was just super badass and cool. I loved his voice actor, his backstory was awesome, he's a legend within Spira. Just an all time all-star quality FF character. If I had to pick a top 6 ever, he's definately in it.

Yuna was classic. A great heroine, who grew stronger, but was weighted with a heavy burden that outweighs possibly any other character in the series outside of Aerieth.

Kimari was cool in his stoic pride, Wakka, and Lulu were solid, and I loved the NPC's for the most part too. The old wise man, the enemies. All great stuff.