I use a few different ones.
The tried and true Texas way, salt and pepper, equal parts. Let's the smoke and meat do the talking.
I have also tried and love, 2 parts Montreal Steak to 1 part Bad Byrons Butt rub. Not completely home made, but it is one of my favs.
And lastly, a good blend of several spices, but still keeping it pretty simple: 4 TBSP Kosher salt, 4 TBSP black pepper, 1 TSP granulated garlic, 1 TSP granulated onion, 1 TSP chili powder, 1 TSP cayenne.