Why is Liferay Portal is best choice in my view

1. Liferay has Rich out-of-the-box functionality in most area like Core Portal, CMS, Collaboration, Social, Mobile and Security etc. For more details you can check out http://www.liferay.com/products/liferay-portal/features/portal.
2. Liferay support Hooks/Extension/Plugins/Custom Development Environment to deliver requisite functionality within limited budget.
3. Liferay’s Open Source nature and architecture help avoid lock-in to a single proprietary vendor based portal product.
4. Liferay has the lowest Total Cost of Ownership compared to its competitors starting with its licensing and getting it up and running through development costs, operational costs, and training and support cost from the perspective of Infrastructure, Development teams, Administration.
5. Liferay introduce new capabilities whether it be AJAX,Mobile, Social and Friendly URLs
6. Liferay is lightweight in its nature. It is quickly to get it up and running, as well as easier to develop and manage. So Liferay improved the Agility in Business execution.
7. Liferay is a mature Enterprise Open Source Portal Product. Liferay community provide 24x7x365 support with 1 hour response time SLA ( in case of Platinum Support Plan). Support includes access to all service packs, hot fixes, notifications of security alerts, phone and web based support.
8. Liferay’ provide Hook and Extension Plugin Model allows to tailor Liferay behavior  as per the business needs without rewriting functionality from scratch.
9. Liferay offers the flexibility to make a full choice of  Application Servers,  Databases, and Operating Systems Platform to run on.
10. Liferay provide a solution that works today and is flexible enough to drive future strategic growth. It is more flexible than SharePoint.