i have late onset restartitis so ive gotten fairly decent experience in everything but bard/resolve dps. first char was a dual wield thief who focused on stacking obscurment, using Deadly Shadow, estrus flask, shadow strike, sneak attack. would replace estrus flask but only option i had at the time, and also helps if you take quin etc, for hybrid damage against stuff strong to one or the other. pretty successful and happy with it. also very good party wise, fits in most groups, just lacks a easy summon.
tried tank, theyre fun, they just really need a ability to direct more enemy damage to themselves, they seem a bit too tanky with no use for it, and non tanks seem too squishy against aoe nukes. needs a way for tank to not nullify damage but take a heavy chunk of it, or have an ability to start taking damage for companions when they get to crit hp. still pretty fun and still works, and the unique items you can get so far probably make the pc the "best" tank. maybe(?). aronas pretty close second in my experiences. party wise they felt the worst to me, not because of their effectiveness, but because of all the classes tanks are not in short supply at all, and we're getting a quin tank sometime so just feels bad compared to others.
black mage... is not bad, but if youre not trying to exploit game mechanics or item swap cheese, basically you get your choice of superior (pref fire based) summon, grease, fireball, then spam them. theres enemies resistant to flame, yes, but the other elements are just not as good. grease just beats everything, they need other elemental spells with effects competitive with grease, like a electricity aoe having a higher than average chance to stun, etc. probably feels the most unfinished out of the classes i tried.
white mage has the most annoying prologue imo (2 white mages with minimal damage fighting rapid encounters), but is a top contender rp wise. from the start you get small changes like holding caits head and healing her, and various alterations through the game. combat wise youre not a conan, or a dark wizard with fireballs, sure, but it makes you feel powerful in its own way being able to help your companions in dialogue other classes couldnt, even if its mostly flavor text. being able to tend their wounds, protect them, just awesomely done. other classes fall behind in comparison, no real options in dialogue to shield your party so far, thief has some however. party wise is also in a very good place, with most of the current healers having alt class kits, and presumably the others getting them in the future, wmages probably have the largest party member pool and variety. you can have a resolve dps and tank, regular dps and tank, atugia and take a extra damage spell to compensate, or same thing with berwyns summoner kit.
altogether though each class is pretty well done, im a bit biased to white mage because i enjoy keeping good and bad people alive, keeps things interesting, and works with rp, but i never had a distinctly "bad" time.
and for bonus points my rp kinda got "corrupted" (pun intended) over time. started quite nice and have slowly fell. only so much smack talk you can take from certain characters before you just want to give them their medicine, by christ. somedays we want to protecc, sometimes we want to save, sometimes we just wanna burn a entire kitsune tree to the ground then invade their homeland