Boey or Henry?

If you really want to build one of them, then I'd go for a +Atk Boey. He'll do more damage (even though that damage is still really low) and he has higher BST if you're interested in using him in the arena.

Well Henry already comes with raventome, something very useful against non-CA archers who target def. But if your playstyle preference is having tight formations, Boey and his default owl tome can be useful. Also Boey has a lot more atk than Henry, something that holds Henry's kill potential back significantly. You can invest raventome on Boey too if you want and it doesn't rely too much on tight positioning.