FFXI has
Ragnarok, so I'm going with that.
I remember I used to help people back in the days with Alexander just because of the song.
XI is filled with musical pearls - Mizuta just keeps cranking out masterpieces.
Some personal favorites:
*
Battle in the Dungeon #2 - even if this only ever plays in dungeons, the rhythm of it can't help but make me think of a cavalry charge, really nice forward momentum here.
*
Awakening - the culmination of the first major story in the game, starts out as if contemplating all events leading up to it, and then just exploding in a continuous, sustained manner that carries the battle throughout, eventually quieting down to reassess the situation before resuming with full force
*
Fighters of the Crystal - applies only to a very limited set of battles in the game, but does one hell of a job at building up and maintaining their tension, and doing justice to their stakes
*
Turmoil - tension and dread all over, especially considering this often played during level-capped battles that used to require pretty tight coordination to succeed at, which also served as major roadblocks to one of the greater stories in the game
*
Fated Strife - this plays whenever one of the cities in the game gets invaded and both players and NPCs are tasked to defend it on multiple fronts at once, usually from rather gigantic beings, and this really emphasizes and chaos and stakes of the situation
*
Roar of the Battle Drums - used to punctuate the large-scale battles present throughout the Crystal War, often interrupting far quieter tracks as armies start approaching contested point, and not stopping until there's a clear winner or loser
*
Feast of the Ladies - the Shantotto track that the Dissidia games don't bother to use even when she's the primary rep for the whole game in them; dances between the playfulness of a Sorceror's Apprentice and the dread of the fact that not only is she no apprentice, but is actually quite the dangerous and competent sociopath
*
The Price - for the final Seekers of Adoulin fight - starts you off with the awe of having you face off against something transcendental, then pushes forward with an amazing sense of triumphant hope
*
Wail of the Void - not the kind of sound you'd associate with battle, because that's not all that's at stake for this one in particular - this of for the final battle of Rhapsodies of Vana'diel, the last major story in the game, so if you're in that battle, either the game's world is about to end, or your history with it is, so there's a wistful sense of parting throughout, punctuated by the fact that the walls of the battle play out scenes from all over the game's world and history, in a "life flashing before your eyes" kind of way.