Gallanza feels like a rehash: Draph male who is one of the chief lieutenants of the empire who wants fights. Already seen him two times before with Ghandharva and Baragona.
I am investing into Gran for now. I've built him to reduce the party's incoming damage, using Phalanax (reduce incoming damage by 40% to 70%), Substitute (redirects all of the party's incoming damage to Gran, increases Gran's defense by 20% to 50%), and Stall (slows' the enemy's actions by up to 50%ish). Due to the long cooldowns of these abilities, I am trying to rotate through each one rather to maximize defense uptime, rather than popping them all off at once.
Unfortunately, while Gran has access to a wide assortment of skills, his unique mechanic, Skybound Arts, works against rotating abilities like this. Gran has to build up to four stacks of Arts for his abilities to activate at maximum effectiveness (ie Phalnax at 70% reduced incoming damage). You build up stacks of Skybound Arts by finishing combos. The shortest combo is three moves. That means to build up four stacks to fire off an ability at maximum effectiveness, I need to use 12 moves, which takes a while. When I am fighting trash mobs, I usually can't even finish the short 3 move combo because they either die so fast, or there are so many mobs attacking that I have to interupt my combo by evading or blocking. Against bosses it is much easier to do combos and build up stacks of arts, but it still takes time, and I might be sitting on a cooldown that is ready to go because I haven't acquired four stacks yet.
For my fourth ability, I keep switching back and forth between using either Armor Break for its mobility and short cooldown (which means I'm not waiting until I reach 4 stacks of Arts to use it) which is great on trash fights for getting me to a living mob so I can do combos and build stacks, or Panacea as my AoE heal on boss fights.
I have heard that Vaseraga can be turned into a tank (presumably he has access to Phalnax and Substitute). If he doesn't have a mechanic like Skybound Arts that incentivizes firing off all of your abilities at once then he might be the better pick.
The white armor Rolan gave to Gran is quite nice. I hope it is added as a skin to the gacha soon.