I have 3 characters on the Bahamut server
My first was a tarutaru. I got him to level 22 as a black mage, and 20 as a white mage. Being a black mage was lots of fun, but I wanted to try some melee classes, and tarutaru aren't good for that sort of thing.
My second character was an elvaan. He's a level 54 dragoon. Don't pick elvaan unless you want to be a paladin. They have very low dexterity, which is essential for most melee classes, and very low MP, which is essential for all spellcasting classes. Furthermore, elvaan get no respect >_<
Also, don't pick dragoon. At higher levels you won't get any party invites, because people will pick higher-damaging classes over dragoon for their party, such as a ranger or a black mage. I had a lot of fun playing a dragoon, and it IS a really cool class, but everyone else thinks it sucks, so you won't get party invites, and therefore, can't level up.
My current character is a hume. Since I was disappointed with my limited ability to change classes as a tarutaru and elvaan, I picked hume because they have balanced stats and can excel at any class. I had also been frustrated with not having enough money, so I made him a thief, and I'm a level 30 thief/ninja right now, and have been enjoying it a great deal.
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Here's a breakdown of the classes you can be:
Standard Jobs: These jobs you have available to you in the beginning of the game
- Black Mage: They deal damage, and lots of it. Blowing stuff up with elemental spells is great fun. Black mages are highly desirable in every party, especially at higher levels. Moderately expensive when you have to buy the higher level spells. Best race for this is tarutaru, second best is hume. Any other race for a black mage is a joke. Best subjob is white mage.
- Monk: These guys specialize in martial arts. I only leveled monk to 15 as a subjob for my warrior, and I've never partied with a high level monk, so I don't have much to say about them, aside from the fact that leveling monk to 15 was quite boring, and I've heard that they get pretty powerful at higher levels.
- Red Mage: Red mage kinda sucks until higher levels. They're a hybrid job, in that they can wear medium armor, use swords, and cast both black and white magic. But they're not as good at magic as either a black mage or a white mage, and they're melee power is a joke. Basically until as a red mage, your job until level 41 is to help the white mage heal, and weaken the enemy with enfeebling magic so that the damage dealing jobs can kill the it more easily. However at higher levels, the red mage gets two essential abilities: refresh, which when cast on another mage gradually refills their MP, and convert, which swaps the Red Mage's MP and HP. So when the red mage gets low on MP, they can convert, making their HP low and MP high, and then heal themselves. This allows the red mage to keep their own MP full, as well as the MP of the other people in the party, making them a very popular choice for parties at higher levels.
- Thief: Until level 15, the thief is basically a really crappy warrior. At 15 they get backstab, which is lots of fun, and Treasure Hunter, which increases the chance of rare items dropping. At 30 they get Trick attack, which allows the thief to focus hate on the tank, which makes them popular in parties. At 45 they get Treasure Hunter II, which makes them money-making machines. Thieves also can pick the locks on chests, and have an ability that increases the amount of money that monsters drop. So if you like money, by a thief. Dexterity is very important for a thief, so mithra is the best race. But mithras are all female, so if you don't want to play a female character like me, pick hume.
- Warrior: Warriors are the tanks until higher levels. At level 5 they get the "Provoke" ability, allowing them to focus the hate on themselves. But at higher levels they can't generate enough hate because they do crappy damage, so the monsters end up killing off the mages. Warrior is basically only used as a subjob for melee classes, and is essential for paladins, for the provoke ability.
- White Mage: Not only popular, but almost absolutely necessary in every party at any level. White mages heal the group, 'nuff said. They also can raise fallen comrades at level 25, and get teleport spells at 37, allowing them to teleport the entire party to one of six different areas spread out around the world, make travel much faster. If you pick white mage, you'll rarely have trouble finding a party.
Advanced jobs: These jobs you have to unlock by doing a quest that's available at level 30
- Bard: Performs the same functions as a red mage, basically. Their most important songs at higher levels refill the party's MP. Bards usually have little trouble finding a party at any level.
- Beastmaster: The only class that has a viable solo career. Every other class almost always requires a party of six people to do well with getting experience. Beastmasters tame monsters and use them to do their fighting. I've never seen a beastmaster in a party, so if you like playing by yourself, pick beastmaster.
- Dark Knight: Moderate damage dealing class. They use scythes and can cast some black magic. I don't recommend Dark Knight, because they are overpopulated, so you'll be competing with lots of other people to join parties, not to mention the fact that people will pick ranger or black mage over you if they are available.
- Dragoon: Has the same basic job as Dark Night, only they use lances and have pet wyverns that fight alongside them. I don't recommend dragoon for reasons mentioned above.
- Ninja: I haven't partied with any higher level ninjas, so I'm not sure what their role is. They can wield two weapons, and they're fast and agile but don't do much damage. Ninja is mainly used as a subjob for warrior, thief, and ranger, because it lets them wield two weapons.
- Paladin: Absolutely essential at higher levels, less essential but highly desirable at lower levels. This class is the best tank in the game. They have great defense, and white magic, and are great at keeping the hate on themselves. If you pick paladin you'll never have problems finding a party
- Ranger: Uses ranged weapons, bows, crossbows, and guns. Highest-damaging class in the game, but incredibly expensive to maintain. If you pick ranger, you'll need a good way to make money
- Samurai: Use great katanas, these guys are skillchain masters. They have abilities that refill their TP, or tech points, which allow them to do multiple weapon skills in a short amount of time. I haven't partied with many high level samurais though, and I've never leveled one myself.
- Summoner: They summon the avatars (or espers, guardian forces, summons, whatever) from the other games. You'll get to use shiva, ifrit, carbuncle, fenrir, garuda, and titan to fight for you. I've never partied with a summoner at higher levels, so I don't know what they do, but at lower levels they basically just use white mage as a subjob and act as the party's healer, because they have a crapload of MP.
Sell crazy someplace else, we're all stocked up here.