Darrin Dawkins Aluminum friction
Cane creek tuff man diaphragm
I carry a couple others, but have never bought into the theory that birds really care. He is either receptive or he is not.
Use a call you are comfortable with, use it in a way which makes you confident, and most importantly be smart and spend more time perfecting your setups, knowledge of the terrain, and how to move on birds.
Way too many folks worry about what call they carry, or how good/bad they call, rather than the importantance of everything else in regards to turkey hunting.