When comparing Material UI vs Spectre, the Slant community recommends Spectre for most people. In the question“What is the best CSS framework?” Spectre is ranked 9th while Material UI is ranked 13th.
Ranked in these QuestionsQuestion Ranking
Pro Perfect for React projects
Really convenient and easy to use components
Pro Adheres really well to the material design standard
Really nice implementation so far
Very clean design compared to bootstrap.
Works well on any device.
Pro Mobile ready
Spectre can be used to create mobile websites easily. With all the regular built in elements (buttons, menus, grids etc).
Contains only the basics, no extra fluff.
Pro Open source
Spectre is used through Github, and is open source.
Con Active development means API changes are frequent
Might be a problem for large projects, but since active development is a good thing, you should consider this rather mild inconvenience weighed against the benefits.