i've been a drk for a while and i got war, sam, and thf lvled for sub... i use thf most often, but while lvling i used:
24-29 ninja (shadows are very useful in qufim)
30-49 thf for sneak attack
50-59 war for double attack
60+ your choice really... each job has its benefits
Thf has SATA nice to have a garunteed hit that won't kill you
war has attack bonus, def bonus (which will help with last resort, berserk
sam has hasso, and meditate which are very useful
nin has shadows to help you pull....
don't really know about other subs, and don't know much about nin sub considering mine is still 21... hope this helps.