For a long time I had "go to" calls but as I've gotten older and wiser (pertaining to turkey hunting) I don't really have that anymore. I carry 6 mouth calls and 2 pot calls (rotate pot calls in my bag some during the season). I generally just go with whatever a bird is answering to. If it's not call A then I'll go to B and so on.
Having said that I do have mouth call brand and cuts I like and generally use those only but that's mostly cause I found the ones that fit and sound good with how I use mouth calls.
I'm pretty much down to Oak Ridge pot calls are about all I use anymore and just rotate in different surface calls throughout the season.
I don't usually start with the same call when I go, I just grab one out of my vest and start there. I may be the exception not the rule though