The best CSS Framework? I don’t know. Complexity moves in mysterious ways. The many interpretations soc model must be satisfied.

1. CSS in CSS (canonical)
2. CSS in HTML (write once and time driven)
3. CSS in JavaScript (framework driven)
4. CSS in Shadow DOM (company/department driven)
5. CSS in Scoped Formats (IDE driven)
6. CSS in Preprocessors (design system driven)

I’d say, choices reflect environmental factors (social or otherwise) at play. If you’re lucky enough to choose, then suitability favors what draws the finish line closer? I’ve no advice since I’d rarely have the time/luxury to choose anyway. I’m usually thinking about the possibility of more types, sub–types (i.e in #1: bem, classless, etc), and the transposition strategy and speed between each class/type.