Pretty long post inbound, just gonna go through unit by unit with my thoughts:
I think Hana is better than Hinata - her speed growth is a lot better and the fact that she’ll get doubles more frequently means she’ll effectively have higher damage anyway. She also has better skill, which means more astra procs and more crits. Hinata is a little more durable, and he starts off quite a bit better than Hana does, but by mid-lategame Hana will be outstripping him pretty hard. Plus she’s super cute. Would definitely add Hana to your team.
I would STRONGLY recommend using Oboro. She’s got a great stat spread and starts off in a great class - the seal skills that they get make Oboro incredibly good at softening tough targets, and she has enough bulk to not really get surprise killed by anything. Her damage is really good and she has “good enough” speed that she’ll double just about anything that’s not a ninja or a samurai unit. At the very least, nothing will be doubling her. She also has access to Rend Heaven (incredibly high proc rate and once again adds “good enough” damage to net Oboro the ORKO), as well as lancefaire for even more ridiculous damage. I personally like to hook Oboro up with a killer lance, and between the high crit rate and the high proc rate of rend heaven she’s basically always getting ORKOs.
Arthur is terrible for anything other than pair up fodder, and for access to one of the greatest child units in the game. Since you’re not recruiting children, I wouldn’t bother.
Charlotte is great pair up fodder, bringing extremely strong pair up bonuses to the table. As an actual unit she requires a lot of investment to be worth anything, but if you choose to invest in Charlotte then she’s going to bring one shot kills to the table like nobody’s business. Make her a berserker, hook her up with a bunch of skill books, and give her a killer axe and she’ll be hitting 50-60 crit rate against male units and 70-80 against female units. Her hit rates will still be pretty shaky, but if you desperately need to kill something in one hit, Charlotte is your best bet. Her speed is much better than Arthurs as well so you won’t have to worry about her getting doubled as much. The real problem with Charlotte is that you recruit her at a pretty awkward time later in the game, which makes using her when she’s first recruited awkward. Of course, this still leaves her as extremely viable pair up fodder. Pair her up with Xander and watch him wreck face as he never worries about his crappy speed stat again.
I don’t really think Setsuna is that great. Basically no reason to use her when Takumi is on your team.
All the ninja units are at least “pretty good” just because ninjas are incredibly good units, but Kaze is pretty notable for having an absolutely insane speed stat. He will basically double everything, is extremely unlikely to miss, and has a pretty good chance to dodge most things. I basically use Kaze every playthrough, so strongly recommending you use him here.
Saizo is the most lame duck of the ninja units, and doesn’t really bring anything exceptional other than the strengths of the ninja class as a whole.
Kagero is also pretty good, since she brings the highest strength growth of any of the ninjas to the table. She’s surprisingly slow but still fast enough to double most things, and her skill isn’t exactly fantastic but her hitrates will be stable. She also packs a pretty good defense stat for a ninja, although she’ll still be pretty squishy. I’m a little iffy on using Kagero, but I use her more often than not.
Odin is terrible as a mage and his stat growths are way too spread out. He’s better as a samurai, but even then the only real reason you should be using him is for his child unit. Wouldn’t take him with you. Shout out to those pair up bonuses though. Odin also has a TERRIBLE recruit time in Revelations - showing up at about the midway point at an insanely low level.
Nyx is basically Charlotte - Mage Edition, except she’s a lot more squishy in exchange for getting some range. Her hit rates are INCREDIBLY bad due to her horrible skill growth, which also means she won’t be hitting proc skills very often and it negatively impacts her crit rates. That being said, her mag stat is insane and she’ll double nearly everything, and if you want to use her then you can just pile a bunch of skill books on her face to correct her problems. She’s your best source of magic-oriented ORKOs, provided she…actually hits whatever you’re trying to kill. If you have to use a tome user, she’s still better than Odin just because she brings spooky damage to the table.
If you’re a male MU then sticking with Felicia is a pretty solid idea - she’s there early and will still be useful lategame as a healbot. Her mag stat is a lot better than Jacobs so she gets more potent heals and, probably more importantly, will still be able to ORKO things lategame with a flame shuriken/explosive shuriken/whatever you wanna call it. Her squishiness is rather unfortunate, but just be a little careful with her and she’s basically useful all game.
I would use Jacob only if you’re a female MU, and even then his mid-lategame falloff is pretty drastic. He basically ends up as a worse-than-felicia healbot if you keep him in the butler tree, and without the benefit of insane flame shuriken damage. He’s more durable, which is a plus, but that’s not really worth the other disadvantages IMO.
Flora is awkward recruitment time - the unit, so I literally never used her. She’s pretty redundant with both Jacob and Felicia.
Elise doesn’t really have an optimal recruit time in Revelations, but she’s still the best healbot in the game with investment. I pretty much use her every playthrough as a result of how adorable she is, but she’s still a pretty great unit and she doesn’t steal xp from anybody since her main source of leveling will just be heals.