It's hard to beat a combo that you have home made and tweaked to perfection.
With that being said, my vote goes to Harley's BBQ rub with a light glaze of slow poke spicy apple BBQ sauce. It's easy and available for me. Plowboys yardbird is pretty good. My buddy that just cleaned the 120 entry field at our last cookoff only uses Harley's and Williams rib tickler and sweet baby rays original cut with vinegar and wild mustang grape jelly.