Google recommends webmasters follow the industry best practice of using responsive web design, namely serving the same HTML for all devices and using only CSS media queries to decide the rendering on each device.
When researching site builder in-depth to decide which one is right and which type is future-proof, it is instructive to look at related services, too. Depending on author's goals, tools extending site creation may be oriented towards presentation or towards interaction.
In this article, let's focus on presentation.
Presentation web services: proven vs. modern, open vs. proprietary tools
For instance, online presentation tools
Conclusion: versatility and openness matter and beat even big brands
It's partly comparing apples with pears, but the two presentation tools other than SlideShare are listed as "Alternatives to SlideShare". Another candidate on the innovative side would be slides.com, but it's difficult to get Google trends for this very much generic brand name.
The trend for slides.com shows: versatility and openness pays. As a percentage, the trend is even stronger than Google Slides'.
Slides.com is open in that there are many options for individual creation. It's versatile service for both publishers with designer skills and non-techies.
Another modern presentation service is Canva. It's open in that there is a vast variety of templates and fonts ("Forget Powerpoint"). In a sense Canva is analogous to Wix: lots of options, suited primarily for non-designers.