
Originally Posted by
Malithar
It largely depends on who you currently have. All of those units are capable, but if for example you already have a strong buffer, then going for Zarg would be a bit of a waste.
Zarga - Solid buffer. He's not as easy to use as some others and he does lack some things, but for now, he's a great source of stat, elemental resist, and damage resistance buffs. Four specific things to point out: 1) He can be made into a provoke evade tank pretty easily. 2) His LB applying -50% general DT can allow you to bypass needing a tank. 3) If you don't need his full rotation in a given fight, you can slot in additional abilities pretty easily (Rikku's Pouch for Eccentric and Pod for -physical DT for example). 4) He's the only unit in the game that can take advantage of the unique attack boost of Berserk. He can Berserk your damage dealer right as they go in for an attack for a unique boost of +150% attack.
Barbie - Competent Tornado chainer. Being able to close chains with Raging Winds is nice and strong for now. Her CDs are all pretty good. I'd say she suffers for two reasons though: 1) Her rotation is kinda shit. Her CDs don't line up well and you'd like to have multiple of them on at the same time, though you're losing duration by doing so. 2) Elle from Xenogears will trounce the magic DPS meta here shortly. Nothing will compete with her for quite a few months. Think Orlandeau and Hyoh at their launch, they set the new bar. She'll be the new benchmark for months on end and shy of GLEX buffs or units, she won't be touched.
Kryla - One of our most competent breakers for now. Others (Loren and 2B mostly, but others are solid too) can do the task. However, they run into issues if the boss self dispels or you need to dispel buffs off of them. Kryla is one of the only breakers that can handle that task really well right now. Beyond that, she has decent imperils baked in and a strong source of fixed damage. Fixed damage generally isn't very useful, but it can serve a niche purpose.
Olive - Olive has largely fallen behind. It's not so much that she's bad, she's just not exceptionally good. She'll get the task done if you need a finisher, bonus points if you're needing a thunder finisher or it's a machine. Beyond that, I wouldn't consider her. Finishers are some of the hardest units to slot into a team. She can be useful for boosting your OTKO ability with Immolation Shot.
Grim lord - No experience with her and I haven't really looked into her. Maybe someone else can weigh in. If I had to guess from looking at her, she's competent and capable, but nothing amazing.
Without knowing what you have, I'd say Kryla > Zarg > Barb > Grim Lord > Olive for priority. Having a strong reliable breaker is pretty key to getting through some of the harder trials.