The one that brings the turkey in! [:@]

I know it sounds trite, but that's the way it works. Personally, I generally try a box first. I've hunted birds that liked 1 box today, a different box tomorrow and the first box the next day. Sometimes I get nothing from my 'go to' box, then switch to a slate and... BINGO!! Same with mouth calls... You never know what a turkey wants to hear!! So, practice with all of them!