ok so im a Memphis guy and all... most of our sauces are very sweet. so we tend not to make our rub with a lot of sweet but their is some in it. as for color the best one I have seen is Killer hogs rub . he claims it has 4 kinds of paprika in it (which would explain the color) many of us Memphians in competition look for some front heat and a little back heat ie white pepper and a trace on red pepper. to sample a rub with IMO proper heat try plowboys yardbird as mentioned above. if you can get your Red (color) amounts right and the Heat balanced the rest is just flavor profiles to be use in moderation. I have also noticed in many commercial brands that the salt content is VERY high. possibly because salt is a cheap additive. but is necessary in a good rub.so I guess I will close in saying keep the salt balanced or a little low (it can always be added) study paprikas and their balance of color...test heat profiles of white black and red pepper. once you get that down work on a touch of sweet with white , brown and turbinado sugars and then the flavor profiles ie: garlic, onion, cumins , etc I hope this helps in your study.