Xisin

Short term fights, there you have it. Final coil isn't short term and BLM outperforms it on every turn. BLM is better on like 80% of coil. T1,2,4,5,6,8,10,11,12,13.
To say BLM DPS is dependent on Selene is not entirely true. It gets a huge boost from it, but it is not dependent on it. Black Mage is the only class able to benefit from it, there you have another perspective.
Getting to move or moves being interrupted is a DPS loss but it is also quite recoverable. On T13, I easily get 510 DPS (unmerged) while having to deal with three+ earth shakers throughout the fight, moving for megaflares...
I don't see why Summoner should have less DPS and more utility. Why?
BLM also has manawall and manaward, thank you. Both very good moves and useful ones. You might as well delete Battle res from SMN, because it's pointless. The enhanced virus is also pointless because whenever you have to use it, a SCH does it.

Difficulty might be subjective, but BLM is piss easy