My party in SIII (the first of the games I beat) was:
Chris was my flame champion-by far my favourite of the three main characters in the game and my favourite character in all of Suikoden, followed by Futch. I loved her character arc across the entire game, both of her suits, and though she wasn't that great at fire magic, her defense was incredible. She would just sit and take all the damage from the enemy while also hitting hard and allowing everyone else to use their best attacks. I love Landis as a character because he's just such a cool creeper...plus he has a pretty nice design. Having a winged/half-humanish character was cool. His scythe was cool looking and I loved all his creepy dialogue throughout the game- he had by the far the most entertaining personality. I played through Nadir's productions with him on the cast too many times to count. I loved hearing him say "Yuh huh, we're all gonna die" before big boss fights while everyone else was either scared or pumped up. He had a Killer Rune, of course.
Edge is a personal favourite character of mine. I love his design, personality, and the Star Dragon Sword. He just seemed like a really cool character to me. Emily was my physical powerhouse on the team (other than my mounted combo)-always doing over 1,000 points of damage every turn. When I had her hitting opponents multiple times every turn she was next to unstoppable. She just put a beatdown on opponents, and her Haziness rune proved a nice defense booster as well.
Futch was mounted on Bright, of course. I thought that Futch was a really cool character, had a great design (I loved his sword), and combined with Bright the two of them were doing extensive damage every turn. They were very useful, and Futch was decent at lightning magic as well.
Chris took damage from the enemy so everyone else was free to attack, Edge primarily with Lightning while Emily, Futch, and Bright did heavy physical damage (as did Chris). Landis did decent damage, but was mainly there purely on fun personality/coolness factor.