At this point I mostly mix my own rubs, probably 90% of the time anyway.
For pork: 1/2 cup of brown sugar, 2T of salt, 1T each: black pepper, cumin, garlic powder, onion powder (I usually go light on the onion powder).
Naaman will tell you, and I will agree, for beef (brisket and ribs anyway) equal parts salt and pepper is a good place start. Throughout the years I've lessened the amount of rub I use on briskets, a lot of commercial BBQ joints and YouTubers go way too heavy in my opinion.
When I do use someone else's rub I like Meat Church's stuff.