I'd like to reiterate that kids aren't required just that I find they can surpass their parents if you opt to invest in them as opposed to the parents. there's no right or wrong way to play.
I'm not saying Camilla is bad, she's a goddess on all difficulties but she can contribute to a child who ends up with more utility and raw power in the end.
As for the kids themselves that I mentioned.
Ophelia is downright broken early game if she inherits duelist blow from Odin and Demoiselle from Elise or something from a fem Corrin can also help her or the rest of the team. If you pick her up late game her options for inherited skills only increase.
I have regularly found that Ophelia with duelists blow and bow breaker can slaughter Takumi without fear or getting hit back at all in 23 and he has a ridiculously low chance to touch her in endgame. Both on hard and lunatic she hits reliably, crits regularly and can melee or nos tank when needed. If you make her a witch her utility gets even better. She's got garbage for reclass options from her friends or partners though.
Velouria comes with a built in heal ( two if you pick her up late), beast killer, high bulk plus dmg and can reclass for extra skills but doesn't really need to. She's nearly unkillable with the beast rune and can swap to beast stone if you need that extra punch without losing too much of her naturally high defense. Now I favour Camilla as her mother for the savage blow + grisly wound combo this also gives her excellent growths where it matters. She's a solid frontliner for the team and can be sent off on her own safely as well.
I've only ever used Midori one and a half times. I was mostly noting that she's not going to end up hitting like a noodle like Kaze since her strength cap will be higher. Though of course forged weapons are a thing and I will never argue that miraculous save isn't a more useful personal skill than hers is. I've used Kaze before and while I prefer saizo over him again i'm not saying he's bad just theorizing ways in which his daughter might be superior but again she may not.
I would also like to speak up in favour of heart sealing Jakob right away being a totally viable and awesome thing if you want it. I have never played a male avatar so I have no idea if early game hero Felicia is even a realistic thing.
Ooh and in terms of the servants I prefer Jakob for the avoid boost though my only really dodgy character was a ninja who with Kagero's dart and a Jakob pairup had like 100 avoid.
On the other hand Gunter is great if you wanna wield axes. Also he makes a lovely movement bot as a Wyvern lord.
I have a lot of feels about fire emblem.
edit:
The people who talk about 17/19 being hell aren't the same ones saying armors suck lol (although chapter 19 does suck as a map), it's relatively simple to cheese both of them (19 in particular is literally a Wyvern Lord Beast Killer stomp, featuring someone like...wait for it...Camilla).
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My Camilla's are always primarily Malig knights because of bolt axe shenanigans. Though I will change her to Wyvern lord to pick up rally defense sometimes. She's usually got Keaton as her partner so when she wants to be physical she gets an added boost to her already massive strength. For me Camilla is always an axe user while I use Effie or Benny as my lancer users, sometimes Xander uses a lance but while he can tank the beastbane hits in 19 there's no need to make him.
17 is mostly about patience and planning for me. Which units do I want in what spot, when do I expect reinforcements and who needs to meet which group of them.
Also chapter 20 can die in a fire. I will take the tedious Gaiden chapter to get the Maltet a million times before that map. Sure it can be cheesed/ mostly skipped but it's still a bad map.