Which WF!Hinoka?

It depends. If you want to keep her base bow or brave bow, I'd say attack. She needs more attack to kill armored units, because even though she can double them, she almost always dies to their counterattack, which is why she needs to just one-shot them.

If you are using firesweep, you should probably go for more speed.

atk/spd bond is her arguably most valuable skill and it's pretty rare, so don't merge her. You can give that to some enemy phase units or heroes that abuse teleportation skills. I gave my copy of atk/spd bond to the owltome upgraded Soren for example.

btw: I fucked up and meant this comment as a reply to the thread itself, not just to this single comment.