The Ranger combines physical strength with an impressive arsenal of healing and attack magic to make for a versatile, balanced fighter. “Jack of all trades, master of none”, the Ranger has no glaring weaknesses. Rangers are an excellent class for soloing, but can also be an asset to any party.
With a lot of hit points and strong physical defense, the Soldier is the best “front lines” fighter. Soldiers can equip powerful weapons and armor and are the only non-subscription class that can also equip shields. A Soldier's primary weakness are magical attacks which can be devastating due to their low intelligence/magic defense.
Wizards have a wide variety of powerful attack spells at their disposal, not to mention different types of buff/debuff magic. Although they can generate staggering amounts of spell damage, Wizards have limited hit points and are physically frail. Their high intelligence gives them a great deal of defensive power against magical attacks.
Merchants are well-rounded in terms of physical prowess, able to match a soldier in terms of attack power and defense so long as their Credit holds up. Magically, a merchant can weather multi-target damage fairly well in spite of poor intelligence growth if built for it, but single-target damage will still be a notable concern. Merchants are highly desirable to parties for their ability to boost the amounts of gold and items that are found.
Conjurers are pure casters that are extremely valuable in a party. They are capable of unleashing a tremendous amount of healing or offensive damage but unlike the Wizard, the majority of their spells are spread out over several turns.
The Ninja is a fast, hard hitter that can bottle the life essence of their enemies into healing items. Unmatched in physical strength, a ninja can be a hard hitter for the entire game but their attack power cannot match that of soldiers and merchants due to the limitation of using Gloves as their main weapon type.