I personally am at the following:

Group 1
5/5 Madrigal Effect
5/5 Minuet Effect

My reasons for this is because the game will be outside of Abyssea before long, where we won't be on just double marches. Sure there will be times with the new EG content will require double march, but we'll see as it comes. Since there's no meriting for enhancing our marches, I feel these two will be most important when we get out of Abyssea, since we will no longer have our attack/acc caps from buffs and atma. Lullabies are nice but won't help terribly on NMs except if they spawn adds that can be BRD-slept, and Finale is great but odds are we'll see our groups of RDMs, /RDMs, and /SCHs handling dispel just fine.

Group 2
1/5 Nightingale
1/5 Troubadour

The reason I haven't finished these yet is because I'm unsure of what to come. At the moment, hate is pathetically easy for DDs to cap and just as much so for mages to avoid capping. However, depending on the new EG content, it might be worth wasting a song slot (ballad for mages, or March/Madrigal/Minuet situationally for tank) for Sirvente/Dirge, especially seeing as at the moment there's no way I'm going for the headache that is the Empyreal harp (Screw you Colorless Souls/Apademak Horns. T_T). Really that second category is likely to just go 5/5 Troubadour/Nightingale or 1/5 Troubadour/Nightingale + 4/5 Foe Sirvente/Adventurer's Dirge based on what happens after Abyssea. :s