Astrea snails , blue legged hermits , cerith snails , and a fighting conch are great additions to the reef I usually add a few at a time . Astreas and ceriths are hermit proof in my experience .

Hermits are def snail killers.
I stick to :

Nassarius for the sand bed
Banded trochus for the rest.

If your able try locate some stomella, there not usually forsale but many reefers have a healthy population and they do wonders keeping your tank clean, + they are tiny :)