DRG is the first thing that comes to mind for me. It has nothing to do with being a DRG main >.>
It would really depend on whether you prefer ranged or melee, though. If melee, I would choose dragoon as they hit high numbers, look pretty cool while getting them and they do have a bit of utility.
If ranged, the biggest numbers are going to be black mage, don't the get something like 10k fire 4s? I haven't leveled it up from 50 so I'm not exactly sure, but that's definitely the hardest hitting ability. I much prefered blm over smn at lv50, but it seems they have reversed roles at lv60 (blm is sometimes seen as annoying, and they've had their aoe nerfed quite a bit compared to smn who is now aoe king and pretty fun to play from all accounts I've heard)
Monk technically has better dps than drg, but you won't see the same big numbers as drg, and they don't have much utility outside of traited mantra and int debuff as others mentioned. DRG has high burst and provides utility for bards/machinst via piercing down and raid wide dps utility in crit increase with Battle Litany. Ninja has a host of utility moves, but the lowest average dps. They do have some bursty moves so you'll occasionally see big numbers, but they are 50-100 dps behind monks and drgs.
MCH has really good burst as well, though, as others have mentioned, both brd and mch changes a lot at lv52, depending on how long you've played the game it might not be an issue to you. They both provide utility and you have pretty much a guaranteed raid spot as every group needs one or the other for mp/tp regen. Bard is better for groups with 2 casters via Foes Requiem, and Mch is better when there are 2 melee via hypercharge. Of the dps jobs, these are the typically the lowest but also offer the most utility.
So first, you need to decide if ranged or melee is your preference. From there you can narrow down the more appropriate job for you to play.