I would say it depend on your comp and the fight.
If the fight requies some huge burst sometimes =DRG totaly.His burst is just crazy and only has 60 sec CD.
If the fight is only dps :MNK is better.
Btw if you do have a SMN,you can consider it like a "MNK" ranged since it's a really strong(or may be the best) dps on a long duration.
But really both are good,MNK is "harder" because if he loose GL3 he become really weak for about 20 sec until he comeback on GL3.Would say DRG is more versatile:strong dps in any case,crazy huge burst,2 stuns,debuff shared with BRD,can offtank a mob for a little if really needed and can reduce his enmity(which we're not suppose to use most of the time but shit happens eh)
