I've tweaked this one over the years and I get good reviews. I make it in a large batch, about a quart, but I'll use tbsp and tsp.
3 tbsp chili powder
1 tbsp cumin
2 tbsp paprika
1 tsp garlic powder
1 tsp onion powder
1 tsp powdered oregano
1 tsp coriander
1/4 tsp celery seeds
Ancho, chipolte or cayenne to taste.
Use a good chili powder, not the 99 cents stuff.
I don't put sugar or salt in my rub. I put it on the meat depending on what I'm smoking. I use turbinado or oven dried brown sugar, a little on beef and a lot more on pork. I like to let the rub work for several hours and prefer overnight.