I fully agree with dylan's view.
In France it will be easier to find SharePoint competencies than Alfresco's.
Note that real high level SP competencies are very busy.
Fundamentally, I would say : if you have internal tech team with strong Java skills, alfresco could be a good choice; if not, prepare a strong budget with an integrator.
Out of the box without technical development, SP remains more powerfull and let users and power users realize sites they could not realize with Alfresco.
By the way, you should choose ten enterprise version of Alfreco, Community version is only for testing or for very small projects.
I fully agree with the Dylan's view. It all depends on what your specific requirements are. The best way to go about comparing the two is to do a request for proposal based on a scenario and to see what the vendors propose.
What features are you needing and what skills does the organisation have? Alfresco and SharePoint customisation are quite difference skill sets. In terms of cost, both have a free edition (Alfresco Community Edition & SharePoint 2013 Foundation Edition), but only enterprise editions contain the records management features.
Critically SharePoint is a platform with no compliance whereas Alfresco is a product with DoD 5015.2 compliance, The SharePoint philosophy is to unite all legacy systems in a web interface that can be accessed from anywhere. To that end almost any data can be connected to SharePoint - as opposed to replicated which would increase storage costs and system complexity - and used in business process automation.
The enterprise edition of Alfresco features records management, but in SharePoint you also get features such as e-Discovery of both SharePoint and Exchange data.
In most geographic areas it's easier to get SharePoint resources than Alfresco, and that also affects costs. On the other hand, Alfresco's interface is often preferred to SharePoint and that can affect adoption. Adoption is usually the biggest problem regardless of the technology choice.
Alfresco aggregates various search providers, but SharePoint has custom search verticals and people directory search built-in, using existing Active Directory data. The search configuration in Alfresco is via XML files but via the web interface in SharePoint: Both are easy but you would need access to the server console to change it in Alfresco which might bridge security boundaries in large organisations.