My house rub is usually dozen or more spices mixed together, using whatever is in the spice cupboard at the time. It always includes kosher salt, 2-3 kinds of black pepper (regular, smoked, Worcestershire, and lemon are my choices), garlic powder (not salt), onion powder (not salt), Italian seasoning, a tiny pinch all spice, and a tiny pinch of cloves, mustard powder, extra oregano, paprika (smoked), cayenne. I don't measure any of it, I just eyeball based on how much finished product I want to make. I usually do 1 1/2 cups, and whizz it in my mini-food processor to blend it all together.
Very similar to what I do but I do add white pepper and cayenne, love the heat and sometimes chipotle powder if I can find it. Yours sounds really good and like you, mine comes out different every time because I never measure amounts.