I like using Lightning, Fang and Sazh. The Cerberus role that they can use from the start is verrrry nice for inflicting lots of damage after the chain gauge is up. Speaking of chaining, Lightning and Sazh both are skilled ravagers, so this task comes very easily as well. Fang has got the Sentinel role covered and is perfect for soaking up damage and emnity, and her debuffing is nice to have as well (though admitingly not as good as Vanille's, but Fang can still get the job done!). As far as buffing goes, no one can mess with Sazh in that department, he obtains Haste at an early part of the game, and imo Haste is one of the most important buffs in the game.

Anywho, they got me throughout the whole game just fine, even though healing was one of the weaker points of the game because Lightning has only Cure/Cura for most of the game, I still managed fine