Slaying bow or guard bow?

So I'm currently running brave bow on my +def -spd LA!Roy and since the counter banner just came out today, I thought about running a more defensive set with close counter

So for reference: Roy has 30 def 30res without skills right now.
I thought about:

Bonfire
Close Counter
Quick riposte 2
Hone cavalry
Close def 3 seal

And either guardbow or slaying bow

He's gonna be supported with gunnthra, who has fortify cavalry and he'll get a wind blessing.
Gonna refine his weapon for def.

With guardbow he would be better at handling ranged units so he can be quite tanky at both types of enemies.
With slaying bow I could run Ignis/ Glacies instead.

That is if I even pull takumi, currently am at 3.5 but I put all my hope in the tempest trial.

What do you think would be better?