I use bootstrap for my own projects because I use it to work and don't have to be distracted with yet another framework.
The part of me that likes extreme DSLs gets a bit of a thrill out of Tailwind but Bootstrap is closer to the original intention of CSS but I'd still like to see something that uses modern css features (like calc() and nesting) to build a design system for a site where the classes are mostly semantic.
Trouble is most designers would rather draw one pretty picture at a time than do the systems thinking it takes to make a design system. There's always been a huge mismatch between what CSS offers and what designers want although we've gotten a huge toolbox (40+ spec documents) that let them do what they need, sometimes with some grace.