A lot of Heat in a Rub comes from Black Pepper as well as any Cayenne or other Hot Chile Powder. This is a popular rub around here and my families favorite...
Try this... It is Mild and compliments different style sauces well...If you want spicier increase Blk Pepper to 1T and add 1T Wht Pepper and 1T Mustard powder. The Foiling Juice, at the bottom, makes a Rib Glaze at the end. You can add 1/4C Ketchup, 2T Cider Vinegar and 2T Mustard to make a more traditional KC Style BBQ Sauce....Anything else, just ask...JJ
Mild Bubba Q Rub
1/2C Sugar in the Raw (Turbinado)
2T Sweet Paprika (Hungarian)
1T Kosher Salt
1T Chili Powder (contains some Cumin and Oregano) Ancho Chile is same without cumin, oregano etc.
1T Granulated Garlic
1T Granulated Onion
1tsp Black Pepper, more if you like
1/2tsp Grnd Allspice
Cayenne or Chipotle Pwd to taste, start with 1/2tsp and go from there.
You may also like this for Ribs...
http://www.smokingmeatforums.com/t/110881/foiling-juice-chef-jimmyj
These both are great Sweet Paprika...