Related
Fang is an interesting Synergist that can be quite effective despite having less Abilities than any other Character. She has access to Veil and Haste, but more importantly she gets the high-powered Abilities Bravera, Faithra, Protectra, and Shellra. These Abilities, exclusive to Fang and Vanille, are more powerful versions of the Abilities they are based on, but have a much shorter duration. You'll have to pay a lot more attention to your buffs if you use them, but the payoff can certainly be worth it.
Hope, like Sazh, eventually gets almost every basic Synergist Ability (though he gains Veil over Sazh's Vigilance). Until Chapter 10, however, Hope is primarily a defensive Synergist, with Abilities like Protect, Shell, and Bar-spells. Which of the two is more useful depends largely on how hard the enemy in question hits.
Lightning is a surprisingly effective Synergist, gaining all of the basic Abilities with the exception of Bar-spells. Her biggest failing is not learning Haste or Vigilance until Crystarium stage 10, however. Once all is said and done, she's quite effective simply because Bar-spells aren't of much use against the toughest enemies anyway. Too bad there's no Barstone in this game.
It takes him a while to get there, but Sazh is the most complete Synergist in the game. He and Hope have very nearly the same set of Abilities, though Sazh gets Vigilance instead of Veil. However, Sazh will first gain access to offensive buffs like Bravery, Faith, and En-spells, making him the offensive Synergist for the first nine chapters of the game.
Along with Fang, Vanille is one of two Characters that has access to Bravera, Faithra, Protectra, and Shellra, high-powered Abilities that have a short duration to balance their extra effectiveness. Unlike Fang, Vanille has a decent number of standard Synergist Abilities as well, including Veil, Vigilance, and the Bar-spells. She is the only Character in the game that doesn't get Haste, however, so she's not very effective as your only Synergist.
Bonus Type
Extended Enhancements