I'd say hammer strike is the best one.
It visually looks to have the fastest lunge (using them both in the air) and the hitbox is the same as normal shoulder charge is.
I do like the clang that shieldbash makes though and it honestly does feel the most satisfying to hit.
Especially when it actually works and suppresses a super.
It's so weird how it can still deal damage...but not suppress.
Shouldn't the whole attack be a suppression effect?