As mentioned in some answers before, there are countless wiki-plattforms with different usage-possibilities and it's on you to cherry-pick because there is nothing like "the best" intranet on the market.
The first and most important step is to clearly define your companies needs regarding intranet functionality. A helpful method is the categorization of intranet-features in a matrix of "must have", "could have" and "should have". This specification prevents a lot of hassle in usage and user-acceptance.
My professional perspective allowed me to get in touch with different Intranet solutions and I can summarize that the Confluence based Intranet called LINCHPIN takes into consideration individual needs because it combines Enterprise Content Management, Extranet capabilities with social features. I experienced how completely different companies launched "their" individually developed LINCHPIN successfully.
This page was inspired by the following question on Quora: What is the best wiki engine for small business intranet documentation?