So I've used Pegasus and Wyvern riders and so far from all the FE games I've played, to me personally, I find wyren riders better.
I just can't stand the hell out of Pegasus. They have horrible HP, Strength and Defense that having good skill,luck and resistance is just pointless. Either I suck using them or that I have no idea how to train them. The only thing they are really good at is for utility purposes and that's just that. I wanted to use Florina but man...she's just...she didn't do it for me.
Wyvern riders on the other hand are more favorable to me. They are the opposite of Pegasus Knights with good defense, strength and skill as well as good hp. Their only downside is their weak res but that's about it.
In my playthroughs of FE, I find the latter the better class but idk, maybe you guys have a say in this so I'd like to know what are your thoughts on these fliers who can easily get bashed by archers....