Right now at least the meta seems to be:
Tanks - Warrior (starts out as Marauder), Dark Knight
Healers - Scholar (actually starts as Arcanist, a pet based DPS class but at level 30 it splits into 2 jobs: Summoner (Pet based DPS) and Scholar (shield based healer with a healing pet, with the pet allowing the Scholar to actively DPS more freely), Astrologian (starts at level 30 but is accessed in the city of Ishgard which cannot be accessed until you complete all of the 2.0-2.55 story quests, can choose between a healing based or shield based stance [cannot be changed mid combat] and has some very powerful group buffs, the biggest one of which is a flat damage boost to everyone in the group)
Melee - Dragoon (starts as Lancer), Ninja (starts as Rogue; however you can't start off as a Rogue at level 1 - you have to start as something else and then switch after completing your level 10 class quest.)
Ranged - Bard (starts as Archer), Machinist (Same as Astrologian: starts at level 30 but is accessed in the city of Ishgard which cannot be accessed until you complete all of the 2.0-2.55 story quests)
But with the expansion coming out in less than a month, the meta is almost definitely going to change some if not completely. So like Veluren said, pick something you think you'll enjoy just to start out and roll with it.
The other classes/jobs are:
Tank - Paladin (starts as Gladiator, and is the stereotypical sword and board heavy defense tank)
Healer - White Mage (starts as Conjurer and is just a straight up healing based healer)
Melee - Monk (starts as Pugilist, and while providing
very solid damage, currently doesn't have any raid utility like NIN and DRG)
Casters - Summoner (mentioned above, a pet based DPS class that also makes heavy uses of DoTs; also has good raid utility currently as the only DPS with the ability to rez dead players, allowing the healer(s) to save their MP and continue healing), Black Mage (powerful pure DPS job which can basically be summed up
right here.)