Kentico and SharePoint both enable organizations to host sites for the internet as well as extranet and intranet sites but they differ in their approach, both functionally and technically, to content management.
Kentico Advantages
Kentico’s primary focus is content management and it was built with web standards and best practices in mind such seo, localization, multi-tenant hosting. It offers a marketplace of addins and webparts to extend and enhance the platform. The ability to move content from a dev environment to staging and production is very simple.
Kentico Disadvantages
Kentico’s approach to content is very modular and it can be confusing for editors. Content can be stored as seperate items within the cms pages tree that is then referenced through web parts. It can als be stored in page templates directly or web parts directly. There is no e-commerce module out-of-the-box.
SharePoint Advantages
The SharePoint publishing experience for editors is more simple and straightfoward. Workflows can be attached to any part of the publishing process. All of the SharePoint features are available to sites including search.
SharePoint Disadvantages
Scaling and localizing a site in SharePoint can be complicated, slow and expensive. Publishing is only a feature of SharePoint and therefore many of the services required to run it are not needed for a site, making it bloated platform if it’s only being used to host sites.
Technology
Both are Microsoft products and use asp.net web forms for their sites. It’s possible to create anasp.net mvc Kentico site through the api but in theory that’s possible with SharePoint as well.
Conclusion
If you already use SharePoint and you need to host a small site then by all means use it. For larger more complex sites, Kentico is the way to go.