look the only version that matters is the original NES version to be honest. Forget all these other versions that purposely try to make each class great in it's own way.

Now going through the NES version
Fighter/knight - can equip all the strongest stuff in the game, extremely powerful and can take a lot of damage, plus minor healing spells at class up, but can be expensive

Thief/Ninja- can equip decent equipment, but even the redmage can equip better swords than a thief until class change. Thieves can run well, but I never run because EXP is a must in this game. It's about average with every thing, the real benefit being FAST at class change, but that's about it.

BB/Master- Best with bare hands, giving you 4 extra weapon spaces, so you can have more of those special weapons for fighters. The bare hands get to be really powerful and they're cheap to equip, by far the cheapest in the game. Low defense though.

RedMage/Wizard- Can use strong weapons, second best to Fighter before class change, after class change Ninja can use the Katana, but otherwise RedMage can use all the weapons as well. Can use both white and black magic spells, and magic is severly limited, but can also deal good damage after magic is gone. Not extremely strong in any category, but is useful.

Whitemage/wizard- Can use all white magic, but magic is SEVERLY limited in the NES game, so honestly, not all that great. Plus magic is expensive and you can't cast it all that much.

Blackmage/wizard- Can use all black magic, but again magic is limited and not all that great. Gets decent attack after buying a catclaw though, but still a redmage ends up being more useful.

I stick with my well known awesome party, or should be well known
Fighter(strong and takes damage)
Fighter(second spot still takes a good amount of damage and great to have another strong hitter)
BlackBelt(with two fighters before they take most of the damage, plus he's extremely cheap for equipping the two fighters)
RedMage(FAST and EXIT for the last dungeon are the only required spells, but it's helpful to have a few others, and when he has no magic he can attack well too)

not only that both Knights learn some white magic at class change, so that's helpful as well.

THE JACKEL