The pecan has some heat to it. The cherry rub is lightly fruity, mildly sweet. The sweet heat is also a good all rounder. You really can't go wrong with any of them.
What I like about these rubs is that they're not too heavy on salt. You can apply them heavily and you won't oversalt your pork butt. In fact, you many want taste as you go and maybe use a little salt if you prefer.