It's a very polarizing choice that would require different playstyles involved. Consider them being mostly in a flier team.
Narcian has the advantage of being able to easily bait and tank Reinhardt as well as virtually any blue unit. Which makes him a great frontliner in these blue dominated matches. His disadvantage is that he excels only at this and has mediocre results against greens and dies to reds. His team would have to probably compensate for it by running two blues.
Cherche (with brave axe) can only tank physical dmg and should never get attacked by mages (a problem in a mage dominated meta), so she requires movement support skill abuse and an escape mechanism. Her damage output (even without flier buffs) is impressive tho and she easily kills most of the heroes she initiates upon.
Choosing one of them for a primary flier team is actually quite a dilemma. I know it's a very subjective question and it depends largely on every person's playstyle, but which one of them do you find better in a flier team?
Personally speaking and having built a flier team myself, I would recommend Cherche over Narcian any day of the weak. Her attack is second highest in the game! That too after Effie who she easily wrecks. I would recommend a skill like draw back or hit and run as an escape mechanism and then using a flier with reposition or something since flier teams do require these tricky plays
There is only 4 green flyers in FEH :
Minerva, Cherche, Camilla and Bunnymilla.
I don't know who is Narcian.
More seriously, Narcian can't have a boon/bane, so he can't fix his low atk, nor is low spd. He will be super vulnerable if he doesn't start his turn next to an ally (for the buffs). Just go for Camilla instead, she is 100% better, especially with braveaxe. Otherwise Cherche for a more offensive, less defensive axe flyer.
Michalis, this poor version of Minerva.
He can't have a boon/bane to modify his stat-line, resulting in him getting killed by most red, all the blue mage, all the green mage and even the bunch of axe wielder that may 2HKO him due ot his poor spd.
AND him getting killed by the grey units too (excluding ninja which have a debuffed/poke role).
He gets wrecked by wrathful clerics and even tho he has a good def, he gets rekt by archers unless he take his Aegis passiv (rip his A-skill then).
I'd prefer Cherche, especially if you have S!Corrin as mage flier. Regarding the roles that your Narcian wants to fulfill, they can be fulfilled better with Camilla. So it is really a question between Cherche and Camilla. Since S!Corrin cannot check Reinhardt, I might give the edge to Camilla in the current meta.
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