There are many content management systems such as Documentum, Stellent, Vignette provide a wide range of solutions such as document management, records management, web content management and much more that what Alfresco has as of today.
However few things to consider for Alfresco are:
1. Open Source
2. Open Standards
3. Single repository for all the solutions
4. Fastest JCR repository
5. Cheaper and low Total Cost of Ownership
6. Runs on wide range of platforms
Some of the commercial closed source companies do not provide advantages listed above.
Alfresco is based on Spring framework with
JSF and Hibernate plus additional open source components.