How about Legendary Marth?? He's very identical to Ayra in regards to stats but he also has more roles than Ayra to fulfill, not to mention a special with the same SP count.
Karla is the most offense focused of the three but also somewhat fragile while Marth is the most supportive of them with his Fire Emblem. Ayra is also offense focused but has similar defenses to Marth but more damaging spec in Regnal Astra. Just use who fits in your team best I guess.
In my opinion between the 3 Ayra is the better one.
Ayra can abuse Slaying edge+Wrath, with her decent bulk she can activate Regnal astra twice in a fight and have both times the special buffed by Wrath, she can run double brazen to make it more deadlier.
Karla can also run something similar with Moonbow thanks to her Vassal's blade having the slaying edge effect and +7dmg but her poor bulk makes her unlikely to be able to activate Moonbow twice while having Wrath active, she needs desperation otherwise after the first fight she won't be able to take any more dmg.
L!Marth is the weakest between the 3 in terms of fighting potential, he needs team support to use his weapon and his special deal less dmg than Regnal astra, also he can't use the same tactic as Ayra and Karla as you would need to swap his weapon to a Slaying edge and i don't think that is a good idea
Honestly, L marth is so boring to use,outside of his blessing I don't use him at all.
Not to say he isn't a good unit it's just for me his skill set bores me,I'm not interested in giving him any investments and with him having such similar stats as ayra there really is no point for me.
Although both(karla and ayra)are some of my favorite fe characters ayra is in my top 5,so I'm rather biased in my opinion.
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