What's your flavor profile going to be? Depending on that, here are some recommendations based on what I put in m brine:
Tuscan (or, savory) brine-
chicken stock
onions
garlic
lemon zest that I've lightly beaten to release essential oils
lemon juice
Worcestershire
salt
a little sugar
fresh herbs (typically for this one, oregano, parsley and basil)
fresh cracked peppercorns
crushed red pepper flakes
the above brine has been instrumental in capturing first place in my recent comps (several other steps as well in the process)
Sweet brine or BBQ brine (sweetness adjusted for desired taste)
salt
brown sugar
Rub
buttermilk (or, apple cider/juice if making sweet, like with pork. I use buttermilk with chicken)
hot sauce (like a cayenne pepper sauce, i.e. Texas Pete or Red Devil)
Worcestershire
garlic
onion
There are other ingredients that could be added, but perhaps some of these may get the creative juices flowing?
Hope that helps...