War is a good sub for a lot of things in game. So is SAM if you go for 2 handed weapons. Hasso and Seigan/ third eye are pretty much a must in things end game anymore.
DRG can be a fun job. That's my wife's main job and she really doesn't play anything else. /SAM is her sub of choice for the damage output You'll here a lot about how drg is falling behind(or fell behind years ago) as a DD and while it may be true it boils down to "do you enjoy it?"
My nin is lvl 14 and i plan on it staying there so i can't give any input on that other than i've seen some damn good ninjas out there taking on all sorts of things by themselves. NIN in abyssea is what RDM was back in the day.