For decades I was strictly a mouth call man, figuring if I couldn't call them in with my favorite mouth call that they just were not going to come. However, in the last few years I have started toying with using pot calls and various strikers and have come to the conclusion that using a combination of mouth calling and the right friction call together is a deadly combination for tough birds. I plan on continuing to use both.
A good box call would probably be an asset, as well, but for now I think I have my bases covered with the mouth calls and pot calls. To me, there just is not enough difference in tonal qualities between box calls and pot calls for me to carry and use both.