Not many DB villains have a truly fleshed out backstory that makes them somewhat sympathetic, or at least makes their actions understandable. Broly was the only one, really, albeit his flat character squandered his potential. Perhaps this backstory could be linked back to something that the DB characters indirectly did in previous arcs, such as the bad guys not being revived in Boo arc.
I would like the villain to be more complex in terms of morality. The only DBS antagonists who aren't unambiguously evil are those who weren't even evil to begin with, and simply ran into the protagonists, albeit one could make a case for Hit still being a hitman. Or Beerus destroying planets for petty reasons. One could also have the villain follow a particular moral code that prevents them from being completely irredeemable, or villains who genuinely want to do good while going the wrong way about it. Zamasu could have been an example of such with better ideas, but ultimately his motivations could basically be summed up as "I want to kill all mortals because I don't like them, the other gods be damned", turning him into an irredeemable hypocrite who fooled himself in believing otherwise.
The villain doesn't even have to be major either. It could be a minor villain who simply causes trouble, but not enough to cause all the goods guys to get involved. This wouldn't require a powerful bad guy, and Goku or Vegeta wouldn't need to show up to stomp him. This leaves room for the likes of Yamcha to shine, even for a short while.