Final Fantasy XIV: Which DPS Class Should I Play?
Melee DPS
Melee DPS are close-range attackers. Focused on combos and careful positioning to inflict the maximum amount of damage.
Monk
The Monk is a lightning fast melee DPS class that revolves around keeping up a buff called "Greased Lightning". The MNK has great sustained DPS on a single target and does the best AoE damage out of all the melee DPS (only at later levels). Most of MNK's attacks are positional, meaning you have to move yourself to the back or side of the enemy, depending on the move you have to use next. It's not required to follow your positionals, but they do alot more damage and will sometimes trigger certain effects. Mastery of positionals and timing is what makes a MNK great. If you like a fast paced technical melee class, you will really like MNK.
Dragoon
Dragoon. The poster-boys of Heavensward. These guys wear incredibly cool looking armor and carry their lances to slay any dragons they come across. Their gameplay involves some buff juggling, some positional damaging, (similar to MNK) and jumping. They have many different jumps that allow you to dive back down and crush your enemies. Dragoons are more of a bursty melee DPS and can do a very good amount of AoE damage. They also have a piercing debuff they can place on enemies that benefits Jobs such as BRD and MCH.
Ninja
Ninjas are a stealthy melee DPS that can use a special ability known as "Ninjutsu." By combining certain "mudras" together, NIN's have a variety of Ninjutsus they can cast once every 20 seconds. (Aoe Damage, DoT, Attack Speed Buff, Burst Damage, Bind, etc...) Ninja has some unique moves that deal with enmity as well. They can take enmity off themselves, give it to someone else, and reduce hate generation on a party member. This makes them a great addition to any party. Ninjas can also use "hide" and walk around while invisible while not in combat. People have been known to use this to skip trash in certain raids. If you're a fan of assassin classes, you should definitely give NIN a try.
Samurai
Physical Ranged DPS
Physical ranged DPS attack foes from a distance. They excel at inflicting sustained damage, and also provide support for companions.
Bard
The Bard is a very mobile ranged physical damage dealer that can play songs to buff their allies. (while sometimes lowering their damage as a consequence) At higher levels, they can play a song that turns them into a caster, giving them much less mobility but much higher damage. The mastery of that song is what determines a great BRD. They even have a song that can lower the magical resistance of their enemies, making them great when paired with a BLM or SMN.
Machinist
The Machinist is very similar to the bard, but it does differ in some ways. The MCH can place a turret of his choice down on the battlefield to do damage. Turrets can also be switched to different modes that buff allies. Like Bard, MCH is a mobile physical damage dealer up until later levels, where they can put an attachment on their gun that makes them do more damage while giving their moves cast times. MCH doesn't do the most damage of the DPS Jobs, but it has fantastic utility.
Magic Ranged DPS
Magical ranged DPS attack foes using a variety of arcane arts. Movement is restricted by casting times, but they excel at inflicting high burst damage.
Black Mage
The Black Mage is a ranged magic caster that focuses on Fire, Ice, and Lightning. The class revolves around balancing buffs known as "Astral Fire" and "Umbral Ice". (And in later levels Enochian, but you don't have to worry about that right now) One buff regenerates your MP while the other makes you do more damage at the cost of more MP. The BLM is very burst-oriented, meaning they only attack once every 2.5-3 seconds, but the amount of damage they do in a single attack is very high. They also have fantastic AoE (area of effect) damage. BLM's can also zip around the battlefield by teleporting to their allies. If you like huge flashy attacks, while also being a stationary turret, BLM is for you.
Summoner
Summoners are the 2nd Job that Arcanist branches into. (the first being SCH) They can summon one of three pets that help you deal damage. Your main source of damage is your DoTs. At later levels, you get very flashy and bursty attacks similar to BLM, but gameplay still mostly revolves around DoTs. Alot of their abilities are instant cast, meaning they have decent mobility. SMN's also use "Aetherflow", but it gives them access to awesome damage abilities rather than healing ones. One of SMN's pets is a tank, which makes them a fantastic solo class as well. They are the only DPS Job that can raise allies from the dead mid-combat. SMN has the best AoE damage in the game.