Green Raven user : Merric or Boey ?

Hi. I guess it's more than enough time for me to build my first Raven tome mage (with Triangle Adept and Bowbreaker), but I'm really not confident in the abilities of the mages I got.

My green mages are :
- Merric 5* (merged +1) +HP -Def nature
- Boey 4* +Atk -Res nature

I know neither of these 2 natures are optimal, but who do you think would be the best ? The aim is obviously to tank archers so Boey's superior def is clearly a huge asset, but I'm a little afraid of his lack of Res to duel with the occasional Blue Mage. Merric has the advantage of having way more Spd and a few more HP.

Or I could switch to a Red Mage for this Raven Bowbreaker build, and use my +Def -HP Sophia. I heard she's good for this too.

So what do you think ?
And good luck on the summons !