Most successful, I haven't tried them on the real thing yet, so I don't know that. However, my new favorite mouth calls are Quaker boy mini mags, I think that is what they are called. These things are considerably smaller than most mouth calls and they fit my pallet to a T. I have been practicing with two of them in my mouth so I can switch between the two with no hand movement and they sound great according to my hunting buddies.

Friction type call, I will have to say Primos Freak with crystal.

just my two cents.