I think granulated has a more similar consistency to sugar, salt, pepper and other spices. I buy mine at Sam's Club in the large shakers for like $5. I don't know if it's that great a quality of spice (I think the brand around here is Tone's or Tony's?) but I figure since it's part of a rub, it'll do.
18.5", 22.5" OTS
Large BGE (chambersuac's)
The Fiery Furnace (chambersuac's)
Big JT's Smokin' BBQ Competition Team