Really the only fights that had a set job list for 8 man content were hard mode darnus and iffy x, and they had multiple setups.
My ls used 3xdrg, 2xwar, 1xpld, 2xwhm for iffy x and 3xdrg, 2xwhm, 2xblm, 1xpld for darnus
AV/CC you could literally use whatever you wanted we did an 8mnk coincounter one time
Warrior could tank anything just as well as pld except for iffy x and darnus after that beauty pld update
brd were awesome in dungeons for collecting chests because of swiftsong, but since you could job swap mid-dungeon brd was never used in the final fight, just buff and swap.
melee DD output was dependant on the boss and the player, one time we had a war out DD all 3 drg on iffy x
play what you want all jobs were useful, dont play something you dont want because its "better" than something else, play what you want and find out how to make it work. All endgame events take time and forming varying strategies to win and you will fit into one of them.