Here is another from an old post.
First, I'd lose the paprika as its flavor is not only subtle, it also doesn't stand up to long cooking. I'd replace it with more flavorful ground chilies, a blend of 2 or, ditching the chili powder as well, a blend of 3. Much more depth.
I'd replace the garlic and onion salts with granulated garlic and onion and change the ratios.
Cayenne has heat but little flavor so I'd drop that and use a flavorful hotter chile in the chile blend above.
I'd alter the black-white pepper ratio.
I'd use thyme as the primary herb, marjoram and perhaps bay in secondary roles.
I'd cut the cumin a little and add a couple or three 'sweet' spices--allspice, ginger and cinnamon--in small quantities.
Salting the meat first, separately, and keeping salt out of the rub, allows you to use as much or as little rub as you wish without affecting salt levels.
Thus:
1/2 c sugar--consider light brown or turbinado
Chile blend:
3 T ancho, 2 T guajillo, 1 T aji amarillo
or
3 T ancho, 2 T guajillo, 1 T cascabel
or
2 T ancho, 1.5 T guajillo, 1 T aji amarillo, .5 T cascabel
1/3 c granulated onion
1/4 c granulated garlic
3 T thyme
1 t marjoram
1 t powdered bay leaf
1.5 t white pepper
1.5 t black pepper
1.5 t allspice
1 t ginger
.5 t cumin
.5 t cinnamon
T=tablespoon t=teaspoon
For best flavor buy quality ingredients!
You'd likely find whole anchos, and cascabels in area markets (you can toast them and grind them yourself) but not the powdered form and not aji amarillos. All are available in ground form from here. (They are also available whole from the same site.)