Skipping past the debate and arguments, I'm gonna be biased and say Corsair.
I always put "I outparse bards." in my /seacom when I seek for merit parties just for kicks. It's funny because pretty much anyone can too :P
Anyways on a serious note, assuming you have a reasonable puller, tons of dds and a whm or rdm like most merit parties are setup, I would say COR for the simple fact that they can do good damage too and a majority of their rolls are catered to melees and give what no bard can.
STP + ATK roll = holy ***
Refresh + Conserve MP = <3
Gogo chain 200~
Long story short: Don't have puller job already? Get BRD. Got a THF or RNG or someone else halfway decent at pulling? Get COR.