THF > BLM > NIN > RNG > MNK/PLD/DRG/DRK/SAM > THF
BRD, BST, and RDM are wildcards in a sense. Of course anyone could be wildcards if they play out of the box(suggested)

... that changes fast thanks to +74 and /NIN and such.
In fact the soon you relize the best way to win in Ballista is like how you win in FFXI. In groups.
BRD NIN BLM PLD MNK WHM > RNG RNG RNG RNG RNG RNG
If you can cover your weaknesses and double your strength you can land a lot of gate breaches. Also playing tactics like luring opponents into ambush works grat.
Best Ballista job? Team mate

(other)