Ford or Chevy?
Given your question, the term "best" is relative. Most people looking to buy a call have a particular sound in their head that they want to hear from a call. When they run a call that produces "that" sound, they have found the call they are looking for. Unfortunately, that sound may or may not be what a particular gobbler wants to hear on a given day in a specific location.
That said, there are a number of folks here on the forum and some not on this forum that can build a great sounding call with most any surface you might want. Let me also say that although certain surface materials have some general sound qualities, there are MANY variables that can be manipulated to create very different sounds from the same surface material. Some of these variables include pot material, pot design, striker material, pressure applied to striker, angle of striker to surface... There are way too many variables to list.
If you have a specific sound that you want to hear, try to formulate a description of that sound. You will need to think about pitch, tone, volume... You will need to know what kind of weather conditions you plan to hunt (moisture, humidity, etc.) and what kind of calling you hope to do with the call (subtle, aggressive, calling across large fields, etc.). Given this information, a good callmaker should be able to help you select the right wood for the pot and striker. Some wood and surface combinations can be incapable of producing certain sounds in a call. That said, I personally would not choose cherry or walnut for a call with either of the surfaces mentioned... but that's just me.
Good luck in finding the call that is right for you.