I would agree with Smoke Ninja, salt and pepper is as universal or all purpose as you can get.
Most of the rubs I have used are designed to compliment a specific type of meat. IE: A sweet rib rub may work great on ribs, but definitely not on a brisket. But some pork rubs may also work on chicken, but you have to be the judge of that.
Maybe the video below will help you....
Arron Franklin's Evolving Base Rub from his video (below)
*Note - his measurements are in "parts","bits", "smidges", and "touches" so these are approximates as seen by the volume added in the video.
Arron starts with an even mixture of salt and pepper for his brisket rub
1/2 cup of course black pepper
1/2 cup of kosher salt
Optional ingredients for Texas style brisket rub
(or an all purpose rub).
1 teaspoon garlic powder
1 teaspoon onion powder
1/2 teaspoon of chili powder
He then states to make this rub for pork add the following
3/4 teaspoon of hungarian paprika
1/2 teaspoon of mustard powder
For ribs use the complete blend above, but double the pepper
He then says to make this a chicken rub add
3 Tablespoons of brown sugar
He says he wouldn't add sugar to a pork rub or a rib rub, because sugar burns over time making it dark, whereas chicken cooks faster so it doesn't seem to burn as easily.
[ame="https://www.youtube.com/watch?v=dGwmaq6y6iU"]BBQ with Franklin: Special Rubs - YouTube[/ame]